diff --git a/README.md b/README.md
index 3905ac3..99a0418 100644
--- a/README.md
+++ b/README.md
@@ -29,10 +29,10 @@ fn main() -> Result<(), Box<dyn Error>> {
             pipeline_name: Some("testPipeline".into()),
             url: Some("https://dev.pipeline.run/url".into())
         })
-        .with_id("/dev/pipeline/run/1")
+        .with_id("/dev/pipeline/run/1".try_into()?)
         .with_source("https://dev.pipeline.run/source".try_into()?)
     )
-    .with_id("271069a8-fc18-44f1-b38f-9d70a1695819")
+    .with_id("271069a8-fc18-44f1-b38f-9d70a1695819".try_into()?)
     .with_source("https://dev.cdevents".try_into()?)
     ;
 
@@ -52,7 +52,7 @@ fn main() -> Result<(), Box<dyn Error>> {
     let cloudevent_received: Event = cloudevent.clone();
     let cdevent_extracted: CDEvent = cloudevent_received.try_into()?;
 
-    assert_eq!(cloudevent.id(), cdevent_extracted.id());
+    assert_eq!(cloudevent.id(), cdevent_extracted.id().to_string());
     assert_eq!(cdevent_expected, cdevent_extracted);
     Ok(())
 }
diff --git a/cdevents-sdk/examples/pipelinerun_finished.rs b/cdevents-sdk/examples/pipelinerun_finished.rs
index 4bfdef6..12a5c07 100644
--- a/cdevents-sdk/examples/pipelinerun_finished.rs
+++ b/cdevents-sdk/examples/pipelinerun_finished.rs
@@ -11,10 +11,10 @@ fn main() -> Result<(), Box<dyn Error>> {
             pipeline_name: Some("testPipeline".into()),
             url: Some("https://dev.pipeline.run/url".into())
         })
-        .with_id("/dev/pipeline/run/1")
+        .with_id("/dev/pipeline/run/1".try_into()?)
         .with_source("https://dev.pipeline.run/source".try_into()?)
     )
-    .with_id("271069a8-fc18-44f1-b38f-9d70a1695819")
+    .with_id("271069a8-fc18-44f1-b38f-9d70a1695819".try_into()?)
     .with_source("https://dev.cdevents".try_into()?)
     ;
 
@@ -34,7 +34,7 @@ fn main() -> Result<(), Box<dyn Error>> {
     let cloudevent_received: Event = cloudevent.clone();
     let cdevent_extracted: CDEvent = cloudevent_received.try_into()?;
 
-    assert_eq!(cloudevent.id(), cdevent_extracted.id());
+    assert_eq!(cloudevent.id(), cdevent_extracted.id().to_string());
     assert_eq!(cdevent_expected, cdevent_extracted);
     Ok(())
 }
diff --git a/cdevents-sdk/src/cdevent.rs b/cdevents-sdk/src/cdevent.rs
index 885da56..ad4b53c 100644
--- a/cdevents-sdk/src/cdevent.rs
+++ b/cdevents-sdk/src/cdevent.rs
@@ -1,4 +1,4 @@
-use crate::{Context, Subject, UriReference};
+use crate::{Context, Id, Subject, UriReference};
 use serde::{
     de::{self, Deserializer, MapAccess, Visitor},
     Deserialize, Serialize,
@@ -22,7 +22,7 @@ pub struct CDEvent {
 impl From<Subject> for CDEvent {
     fn from(subject: Subject) -> Self {
         let context = Context {
-            ty: subject.ty().into(),
+            ty: subject.content().ty().into(),
             ..Default::default()
         };
         Self {
@@ -46,12 +46,12 @@ impl CDEvent {
     }
 
     /// see <https://github.com/cdevents/spec/blob/main/spec.md#id-context>
-    pub fn id(&self) -> &str {
-        self.context.id.as_str()
+    pub fn id(&self) -> &Id {
+        &self.context.id
     }
 
-    pub fn with_id<T>(mut self, v: T) -> Self where T: Into<String> {
-        self.context.id = v.into();
+    pub fn with_id(mut self, v: Id) -> Self {
+        self.context.id = v;
         self
     }
 
@@ -83,8 +83,8 @@ impl CDEvent {
     /// see <https://github.com/cdevents/spec/blob/main/spec.md#type-context>
     /// derived from subject.content
     pub fn ty(&self) -> &str {
-        //self.context.ty()
-        self.subject.ty()
+        //self.subject.content().ty()
+        self.context.ty.as_str()
     }
 
     /// see <https://github.com/cdevents/spec/blob/main/spec.md#customdata>
@@ -199,14 +199,10 @@ impl<> proptest::arbitrary::Arbitrary for CDEvent {
         use proptest::prelude::*;
         (
             any::<Subject>(),
-            "\\PC*",
-            any::<Option<UriReference>>(),
+            any::<Id>(),
+            any::<UriReference>(),
         ).prop_map(|(subject, id, source)| {
-            let mut cdevent = CDEvent::from(subject).with_id(id);
-            if let Some(source) = source {
-                cdevent = cdevent.with_source(source);
-            }
-            cdevent
+            CDEvent::from(subject).with_id(id).with_source(source)
         }).boxed()
     }
 }
diff --git a/cdevents-sdk/src/cloudevents.rs b/cdevents-sdk/src/cloudevents.rs
index f7fc72d..0c674be 100644
--- a/cdevents-sdk/src/cloudevents.rs
+++ b/cdevents-sdk/src/cloudevents.rs
@@ -68,10 +68,10 @@ mod tests {
     fn test_into_cloudevent() -> Result<(), Box<dyn std::error::Error>> {
         let cdevent = CDEvent::from(
             Subject::from(build_queued::Content{})
-                .with_id("subject123")
+                .with_id("subject123".try_into()?)
                 .with_source("/event/source/123".try_into()?)
         )
-        .with_id("271069a8-fc18-44f1-b38f-9d70a1695819")
+        .with_id("271069a8-fc18-44f1-b38f-9d70a1695819".try_into()?)
         .with_source("https://dev.cdevents".try_into()?)
         ;
 
@@ -82,11 +82,11 @@ mod tests {
         assert_eq!(cloudevent_via_builder, cloudevent);
 
         assert_eq!(cloudevent.id(), "271069a8-fc18-44f1-b38f-9d70a1695819");
-        assert_eq!(cloudevent.id(), cdevent.id());
+        assert_eq!(cloudevent.id(), cdevent.id().to_string());
 
         let (_, _, data) = cloudevent.take_data();
         let cdevent_extracted: CDEvent = data.ok_or(Error::DataNotFoundInCloudEvent)?.try_into()?;
-        assert_eq!(cloudevent.id(), cdevent_extracted.id());
+        assert_eq!(cloudevent.id(), cdevent_extracted.id().to_string());
         assert_eq!(cdevent, cdevent_extracted);
         Ok(())
     }
diff --git a/cdevents-sdk/src/context.rs b/cdevents-sdk/src/context.rs
index cd891f4..7845c5b 100644
--- a/cdevents-sdk/src/context.rs
+++ b/cdevents-sdk/src/context.rs
@@ -1,12 +1,12 @@
 use serde::{Deserialize, Serialize};
 
-use crate::UriReference;
+use crate::{Id, UriReference};
 
 #[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
 #[serde(deny_unknown_fields)]
 pub(crate) struct Context {
     pub(crate) version: String,
-    pub(crate) id: String,
+    pub(crate) id: Id,
     pub(crate) source: UriReference,
     #[serde(rename = "type")]
     pub(crate) ty: String,
@@ -18,8 +18,8 @@ impl Default for Context {
     fn default() -> Self {
         Self {
             version: "0.3.0".into(),
-            id: "00000000-0000-0000-0000-000000000000".into(),
-            source: UriReference::default(),
+            id: Id::default(),
+            source: "/undef".try_into().expect("/undef is a valid uri-reference"),
             ty: "dev.cdevents.undef.undef.0.0.0".into(),
             timestamp: time::OffsetDateTime::now_utc(),
         }
diff --git a/cdevents-sdk/src/error.rs b/cdevents-sdk/src/error.rs
index 5d7260b..51ac340 100644
--- a/cdevents-sdk/src/error.rs
+++ b/cdevents-sdk/src/error.rs
@@ -1,5 +1,7 @@
 use thiserror::Error;
 
+// type Result<T> = std::result::Result<T, Error>;
+
 #[derive(Error, Debug)]
 pub enum Error {
     #[error("Empty data in cloudevent")]
@@ -10,4 +12,6 @@ pub enum Error {
     SerdeJsonError( #[from] serde_json::Error),
     #[error("unknown error")]
     Unknown,
+    #[error("{0} should be non-empty")]
+    EmptyString(&'static str)
 }
diff --git a/cdevents-sdk/src/generated/artifact_packaged.rs b/cdevents-sdk/src/generated/artifact_packaged.rs
index 3900f77..e4472a7 100644
--- a/cdevents-sdk/src/generated/artifact_packaged.rs
+++ b/cdevents-sdk/src/generated/artifact_packaged.rs
@@ -17,7 +17,7 @@ pub struct Content {
 #[serde(deny_unknown_fields)]
 pub struct ContentChange {
     #[serde(rename = "id",)]
-    pub id: String,
+    pub id: crate::Id,
     #[serde(rename = "source", default, skip_serializing_if = "Option::is_none",)]
     pub source: Option<crate::UriReference>,
 }
diff --git a/cdevents-sdk/src/generated/branch_created.rs b/cdevents-sdk/src/generated/branch_created.rs
index 8c479f9..99f44c3 100644
--- a/cdevents-sdk/src/generated/branch_created.rs
+++ b/cdevents-sdk/src/generated/branch_created.rs
@@ -17,7 +17,7 @@ pub struct Content {
 #[serde(deny_unknown_fields)]
 pub struct ContentRepository {
     #[serde(rename = "id",)]
-    pub id: String,
+    pub id: crate::Id,
     #[serde(rename = "source", default, skip_serializing_if = "Option::is_none",)]
     pub source: Option<crate::UriReference>,
 }
diff --git a/cdevents-sdk/src/generated/branch_deleted.rs b/cdevents-sdk/src/generated/branch_deleted.rs
index 8c479f9..99f44c3 100644
--- a/cdevents-sdk/src/generated/branch_deleted.rs
+++ b/cdevents-sdk/src/generated/branch_deleted.rs
@@ -17,7 +17,7 @@ pub struct Content {
 #[serde(deny_unknown_fields)]
 pub struct ContentRepository {
     #[serde(rename = "id",)]
-    pub id: String,
+    pub id: crate::Id,
     #[serde(rename = "source", default, skip_serializing_if = "Option::is_none",)]
     pub source: Option<crate::UriReference>,
 }
diff --git a/cdevents-sdk/src/generated/change_abandoned.rs b/cdevents-sdk/src/generated/change_abandoned.rs
index 8c479f9..99f44c3 100644
--- a/cdevents-sdk/src/generated/change_abandoned.rs
+++ b/cdevents-sdk/src/generated/change_abandoned.rs
@@ -17,7 +17,7 @@ pub struct Content {
 #[serde(deny_unknown_fields)]
 pub struct ContentRepository {
     #[serde(rename = "id",)]
-    pub id: String,
+    pub id: crate::Id,
     #[serde(rename = "source", default, skip_serializing_if = "Option::is_none",)]
     pub source: Option<crate::UriReference>,
 }
diff --git a/cdevents-sdk/src/generated/change_created.rs b/cdevents-sdk/src/generated/change_created.rs
index 8c479f9..99f44c3 100644
--- a/cdevents-sdk/src/generated/change_created.rs
+++ b/cdevents-sdk/src/generated/change_created.rs
@@ -17,7 +17,7 @@ pub struct Content {
 #[serde(deny_unknown_fields)]
 pub struct ContentRepository {
     #[serde(rename = "id",)]
-    pub id: String,
+    pub id: crate::Id,
     #[serde(rename = "source", default, skip_serializing_if = "Option::is_none",)]
     pub source: Option<crate::UriReference>,
 }
diff --git a/cdevents-sdk/src/generated/change_merged.rs b/cdevents-sdk/src/generated/change_merged.rs
index 8c479f9..99f44c3 100644
--- a/cdevents-sdk/src/generated/change_merged.rs
+++ b/cdevents-sdk/src/generated/change_merged.rs
@@ -17,7 +17,7 @@ pub struct Content {
 #[serde(deny_unknown_fields)]
 pub struct ContentRepository {
     #[serde(rename = "id",)]
-    pub id: String,
+    pub id: crate::Id,
     #[serde(rename = "source", default, skip_serializing_if = "Option::is_none",)]
     pub source: Option<crate::UriReference>,
 }
diff --git a/cdevents-sdk/src/generated/change_reviewed.rs b/cdevents-sdk/src/generated/change_reviewed.rs
index 8c479f9..99f44c3 100644
--- a/cdevents-sdk/src/generated/change_reviewed.rs
+++ b/cdevents-sdk/src/generated/change_reviewed.rs
@@ -17,7 +17,7 @@ pub struct Content {
 #[serde(deny_unknown_fields)]
 pub struct ContentRepository {
     #[serde(rename = "id",)]
-    pub id: String,
+    pub id: crate::Id,
     #[serde(rename = "source", default, skip_serializing_if = "Option::is_none",)]
     pub source: Option<crate::UriReference>,
 }
diff --git a/cdevents-sdk/src/generated/change_updated.rs b/cdevents-sdk/src/generated/change_updated.rs
index 8c479f9..99f44c3 100644
--- a/cdevents-sdk/src/generated/change_updated.rs
+++ b/cdevents-sdk/src/generated/change_updated.rs
@@ -17,7 +17,7 @@ pub struct Content {
 #[serde(deny_unknown_fields)]
 pub struct ContentRepository {
     #[serde(rename = "id",)]
-    pub id: String,
+    pub id: crate::Id,
     #[serde(rename = "source", default, skip_serializing_if = "Option::is_none",)]
     pub source: Option<crate::UriReference>,
 }
diff --git a/cdevents-sdk/src/generated/incident_detected.rs b/cdevents-sdk/src/generated/incident_detected.rs
index 6d0c62a..303f33b 100644
--- a/cdevents-sdk/src/generated/incident_detected.rs
+++ b/cdevents-sdk/src/generated/incident_detected.rs
@@ -9,7 +9,7 @@ use serde::{Serialize, Deserialize};
 #[serde(deny_unknown_fields)]
 pub struct Content {
     #[serde(rename = "artifactId", default, skip_serializing_if = "Option::is_none",)]
-    pub artifact_id: Option<String>,
+    pub artifact_id: Option<crate::Id>,
     #[serde(rename = "description", default, skip_serializing_if = "Option::is_none",)]
     pub description: Option<String>,
     #[serde(rename = "environment",)]
@@ -23,7 +23,7 @@ pub struct Content {
 #[serde(deny_unknown_fields)]
 pub struct ContentService {
     #[serde(rename = "id",)]
-    pub id: String,
+    pub id: crate::Id,
     #[serde(rename = "source", default, skip_serializing_if = "Option::is_none",)]
     pub source: Option<crate::UriReference>,
 }
@@ -33,7 +33,7 @@ pub struct ContentService {
 #[serde(deny_unknown_fields)]
 pub struct ContentEnvironment {
     #[serde(rename = "id",)]
-    pub id: String,
+    pub id: crate::Id,
     #[serde(rename = "source", default, skip_serializing_if = "Option::is_none",)]
     pub source: Option<crate::UriReference>,
 }
diff --git a/cdevents-sdk/src/generated/incident_reported.rs b/cdevents-sdk/src/generated/incident_reported.rs
index ee90dae..a4ac0c1 100644
--- a/cdevents-sdk/src/generated/incident_reported.rs
+++ b/cdevents-sdk/src/generated/incident_reported.rs
@@ -9,7 +9,7 @@ use serde::{Serialize, Deserialize};
 #[serde(deny_unknown_fields)]
 pub struct Content {
     #[serde(rename = "artifactId", default, skip_serializing_if = "Option::is_none",)]
-    pub artifact_id: Option<String>,
+    pub artifact_id: Option<crate::Id>,
     #[serde(rename = "description", default, skip_serializing_if = "Option::is_none",)]
     pub description: Option<String>,
     #[serde(rename = "environment",)]
@@ -25,7 +25,7 @@ pub struct Content {
 #[serde(deny_unknown_fields)]
 pub struct ContentService {
     #[serde(rename = "id",)]
-    pub id: String,
+    pub id: crate::Id,
     #[serde(rename = "source", default, skip_serializing_if = "Option::is_none",)]
     pub source: Option<crate::UriReference>,
 }
@@ -35,7 +35,7 @@ pub struct ContentService {
 #[serde(deny_unknown_fields)]
 pub struct ContentEnvironment {
     #[serde(rename = "id",)]
-    pub id: String,
+    pub id: crate::Id,
     #[serde(rename = "source", default, skip_serializing_if = "Option::is_none",)]
     pub source: Option<crate::UriReference>,
 }
diff --git a/cdevents-sdk/src/generated/incident_resolved.rs b/cdevents-sdk/src/generated/incident_resolved.rs
index 6d0c62a..303f33b 100644
--- a/cdevents-sdk/src/generated/incident_resolved.rs
+++ b/cdevents-sdk/src/generated/incident_resolved.rs
@@ -9,7 +9,7 @@ use serde::{Serialize, Deserialize};
 #[serde(deny_unknown_fields)]
 pub struct Content {
     #[serde(rename = "artifactId", default, skip_serializing_if = "Option::is_none",)]
-    pub artifact_id: Option<String>,
+    pub artifact_id: Option<crate::Id>,
     #[serde(rename = "description", default, skip_serializing_if = "Option::is_none",)]
     pub description: Option<String>,
     #[serde(rename = "environment",)]
@@ -23,7 +23,7 @@ pub struct Content {
 #[serde(deny_unknown_fields)]
 pub struct ContentService {
     #[serde(rename = "id",)]
-    pub id: String,
+    pub id: crate::Id,
     #[serde(rename = "source", default, skip_serializing_if = "Option::is_none",)]
     pub source: Option<crate::UriReference>,
 }
@@ -33,7 +33,7 @@ pub struct ContentService {
 #[serde(deny_unknown_fields)]
 pub struct ContentEnvironment {
     #[serde(rename = "id",)]
-    pub id: String,
+    pub id: crate::Id,
     #[serde(rename = "source", default, skip_serializing_if = "Option::is_none",)]
     pub source: Option<crate::UriReference>,
 }
diff --git a/cdevents-sdk/src/generated/mod.rs b/cdevents-sdk/src/generated/mod.rs
index c64f14e..47f92f2 100644
--- a/cdevents-sdk/src/generated/mod.rs
+++ b/cdevents-sdk/src/generated/mod.rs
@@ -339,14 +339,140 @@ impl Content {
         }
     }
 
-    pub fn subject_predicate(&self) -> (&'static str, &'static str){
-        let mut split = self.ty().split('.');
-        (
-            split.nth(2).expect("fargment 2 of ty should always exists"),
-            split.nth(3).expect("fargment 3 of ty should always exists")
-        )
+    pub fn subject(&self) -> &'static str {
+        match self {
+            Self::ArtifactPackaged(_) => "artifact",
+            Self::ArtifactPublished(_) => "artifact",
+            Self::ArtifactSigned(_) => "artifact",
+            Self::BranchCreated(_) => "branch",
+            Self::BranchDeleted(_) => "branch",
+            Self::BuildFinished(_) => "build",
+            Self::BuildQueued(_) => "build",
+            Self::BuildStarted(_) => "build",
+            Self::ChangeAbandoned(_) => "change",
+            Self::ChangeCreated(_) => "change",
+            Self::ChangeMerged(_) => "change",
+            Self::ChangeReviewed(_) => "change",
+            Self::ChangeUpdated(_) => "change",
+            Self::EnvironmentCreated(_) => "environment",
+            Self::EnvironmentDeleted(_) => "environment",
+            Self::EnvironmentModified(_) => "environment",
+            Self::IncidentDetected(_) => "incident",
+            Self::IncidentReported(_) => "incident",
+            Self::IncidentResolved(_) => "incident",
+            Self::PipelinerunFinished(_) => "pipelineRun",
+            Self::PipelinerunQueued(_) => "pipelineRun",
+            Self::PipelinerunStarted(_) => "pipelineRun",
+            Self::RepositoryCreated(_) => "repository",
+            Self::RepositoryDeleted(_) => "repository",
+            Self::RepositoryModified(_) => "repository",
+            Self::ServiceDeployed(_) => "service",
+            Self::ServicePublished(_) => "service",
+            Self::ServiceRemoved(_) => "service",
+            Self::ServiceRolledback(_) => "service",
+            Self::ServiceUpgraded(_) => "service",
+            Self::TaskrunFinished(_) => "taskRun",
+            Self::TaskrunStarted(_) => "taskRun",
+            Self::TestcaserunFinished(_) => "testCaseRun",
+            Self::TestcaserunQueued(_) => "testCaseRun",
+            Self::TestcaserunStarted(_) => "testCaseRun",
+            Self::TestoutputPublished(_) => "testOutput",
+            Self::TestsuiterunFinished(_) => "testSuiteRun",
+            Self::TestsuiterunQueued(_) => "testSuiteRun",
+            Self::TestsuiterunStarted(_) => "testSuiteRun",
+        }
     }
 
+    pub fn predicate(&self) -> &'static str {
+        match self {
+            Self::ArtifactPackaged(_) => "packaged",
+            Self::ArtifactPublished(_) => "published",
+            Self::ArtifactSigned(_) => "signed",
+            Self::BranchCreated(_) => "created",
+            Self::BranchDeleted(_) => "deleted",
+            Self::BuildFinished(_) => "finished",
+            Self::BuildQueued(_) => "queued",
+            Self::BuildStarted(_) => "started",
+            Self::ChangeAbandoned(_) => "abandoned",
+            Self::ChangeCreated(_) => "created",
+            Self::ChangeMerged(_) => "merged",
+            Self::ChangeReviewed(_) => "reviewed",
+            Self::ChangeUpdated(_) => "updated",
+            Self::EnvironmentCreated(_) => "created",
+            Self::EnvironmentDeleted(_) => "deleted",
+            Self::EnvironmentModified(_) => "modified",
+            Self::IncidentDetected(_) => "detected",
+            Self::IncidentReported(_) => "reported",
+            Self::IncidentResolved(_) => "resolved",
+            Self::PipelinerunFinished(_) => "finished",
+            Self::PipelinerunQueued(_) => "queued",
+            Self::PipelinerunStarted(_) => "started",
+            Self::RepositoryCreated(_) => "created",
+            Self::RepositoryDeleted(_) => "deleted",
+            Self::RepositoryModified(_) => "modified",
+            Self::ServiceDeployed(_) => "deployed",
+            Self::ServicePublished(_) => "published",
+            Self::ServiceRemoved(_) => "removed",
+            Self::ServiceRolledback(_) => "rolledback",
+            Self::ServiceUpgraded(_) => "upgraded",
+            Self::TaskrunFinished(_) => "finished",
+            Self::TaskrunStarted(_) => "started",
+            Self::TestcaserunFinished(_) => "finished",
+            Self::TestcaserunQueued(_) => "queued",
+            Self::TestcaserunStarted(_) => "started",
+            Self::TestoutputPublished(_) => "published",
+            Self::TestsuiterunFinished(_) => "finished",
+            Self::TestsuiterunQueued(_) => "queued",
+            Self::TestsuiterunStarted(_) => "started",
+        }
+    }
+}
+
+// due to inconstency in case/format the subject could be not be extracted from the context.type (ty), jsonshema $id, spec filename (shema, examples)
+pub fn extract_subject_predicate(ty: &str) -> Option<(&str, &str)>{
+    // let mut split = ty.split('.');
+    match ty {
+        ARTIFACT_PACKAGED => Some(("artifact", "packaged")),
+        ARTIFACT_PUBLISHED => Some(("artifact", "published")),
+        ARTIFACT_SIGNED => Some(("artifact", "signed")),
+        BRANCH_CREATED => Some(("branch", "created")),
+        BRANCH_DELETED => Some(("branch", "deleted")),
+        BUILD_FINISHED => Some(("build", "finished")),
+        BUILD_QUEUED => Some(("build", "queued")),
+        BUILD_STARTED => Some(("build", "started")),
+        CHANGE_ABANDONED => Some(("change", "abandoned")),
+        CHANGE_CREATED => Some(("change", "created")),
+        CHANGE_MERGED => Some(("change", "merged")),
+        CHANGE_REVIEWED => Some(("change", "reviewed")),
+        CHANGE_UPDATED => Some(("change", "updated")),
+        ENVIRONMENT_CREATED => Some(("environment", "created")),
+        ENVIRONMENT_DELETED => Some(("environment", "deleted")),
+        ENVIRONMENT_MODIFIED => Some(("environment", "modified")),
+        INCIDENT_DETECTED => Some(("incident", "detected")),
+        INCIDENT_REPORTED => Some(("incident", "reported")),
+        INCIDENT_RESOLVED => Some(("incident", "resolved")),
+        PIPELINERUN_FINISHED => Some(("pipelineRun", "finished")),
+        PIPELINERUN_QUEUED => Some(("pipelineRun", "queued")),
+        PIPELINERUN_STARTED => Some(("pipelineRun", "started")),
+        REPOSITORY_CREATED => Some(("repository", "created")),
+        REPOSITORY_DELETED => Some(("repository", "deleted")),
+        REPOSITORY_MODIFIED => Some(("repository", "modified")),
+        SERVICE_DEPLOYED => Some(("service", "deployed")),
+        SERVICE_PUBLISHED => Some(("service", "published")),
+        SERVICE_REMOVED => Some(("service", "removed")),
+        SERVICE_ROLLEDBACK => Some(("service", "rolledback")),
+        SERVICE_UPGRADED => Some(("service", "upgraded")),
+        TASKRUN_FINISHED => Some(("taskRun", "finished")),
+        TASKRUN_STARTED => Some(("taskRun", "started")),
+        TESTCASERUN_FINISHED => Some(("testCaseRun", "finished")),
+        TESTCASERUN_QUEUED => Some(("testCaseRun", "queued")),
+        TESTCASERUN_STARTED => Some(("testCaseRun", "started")),
+        TESTOUTPUT_PUBLISHED => Some(("testOutput", "published")),
+        TESTSUITERUN_FINISHED => Some(("testSuiteRun", "finished")),
+        TESTSUITERUN_QUEUED => Some(("testSuiteRun", "queued")),
+        TESTSUITERUN_STARTED => Some(("testSuiteRun", "started")),
+        _ => None,
+    }
 }
 
 impl From<artifact_packaged::Content> for Content {
@@ -595,3 +721,91 @@ impl<> proptest::arbitrary::Arbitrary for Content {
         ].boxed()
     }
 }
+
+// #[cfg(test)]
+// mod tests {
+//     use super::*;
+// 
+//     #[test]
+//     fn test_true() {
+//         
+//         assert_eq!(extract_subject_predicate(ARTIFACT_PACKAGED), Some(("artifact","packaged")));
+//         
+//         assert_eq!(extract_subject_predicate(ARTIFACT_PUBLISHED), Some(("artifact","published")));
+//         
+//         assert_eq!(extract_subject_predicate(ARTIFACT_SIGNED), Some(("artifact","signed")));
+//         
+//         assert_eq!(extract_subject_predicate(BRANCH_CREATED), Some(("branch","created")));
+//         
+//         assert_eq!(extract_subject_predicate(BRANCH_DELETED), Some(("branch","deleted")));
+//         
+//         assert_eq!(extract_subject_predicate(BUILD_FINISHED), Some(("build","finished")));
+//         
+//         assert_eq!(extract_subject_predicate(BUILD_QUEUED), Some(("build","queued")));
+//         
+//         assert_eq!(extract_subject_predicate(BUILD_STARTED), Some(("build","started")));
+//         
+//         assert_eq!(extract_subject_predicate(CHANGE_ABANDONED), Some(("change","abandoned")));
+//         
+//         assert_eq!(extract_subject_predicate(CHANGE_CREATED), Some(("change","created")));
+//         
+//         assert_eq!(extract_subject_predicate(CHANGE_MERGED), Some(("change","merged")));
+//         
+//         assert_eq!(extract_subject_predicate(CHANGE_REVIEWED), Some(("change","reviewed")));
+//         
+//         assert_eq!(extract_subject_predicate(CHANGE_UPDATED), Some(("change","updated")));
+//         
+//         assert_eq!(extract_subject_predicate(ENVIRONMENT_CREATED), Some(("environment","created")));
+//         
+//         assert_eq!(extract_subject_predicate(ENVIRONMENT_DELETED), Some(("environment","deleted")));
+//         
+//         assert_eq!(extract_subject_predicate(ENVIRONMENT_MODIFIED), Some(("environment","modified")));
+//         
+//         assert_eq!(extract_subject_predicate(INCIDENT_DETECTED), Some(("incident","detected")));
+//         
+//         assert_eq!(extract_subject_predicate(INCIDENT_REPORTED), Some(("incident","reported")));
+//         
+//         assert_eq!(extract_subject_predicate(INCIDENT_RESOLVED), Some(("incident","resolved")));
+//         
+//         assert_eq!(extract_subject_predicate(PIPELINERUN_FINISHED), Some(("pipelineRun","finished")));
+//         
+//         assert_eq!(extract_subject_predicate(PIPELINERUN_QUEUED), Some(("pipelineRun","queued")));
+//         
+//         assert_eq!(extract_subject_predicate(PIPELINERUN_STARTED), Some(("pipelineRun","started")));
+//         
+//         assert_eq!(extract_subject_predicate(REPOSITORY_CREATED), Some(("repository","created")));
+//         
+//         assert_eq!(extract_subject_predicate(REPOSITORY_DELETED), Some(("repository","deleted")));
+//         
+//         assert_eq!(extract_subject_predicate(REPOSITORY_MODIFIED), Some(("repository","modified")));
+//         
+//         assert_eq!(extract_subject_predicate(SERVICE_DEPLOYED), Some(("service","deployed")));
+//         
+//         assert_eq!(extract_subject_predicate(SERVICE_PUBLISHED), Some(("service","published")));
+//         
+//         assert_eq!(extract_subject_predicate(SERVICE_REMOVED), Some(("service","removed")));
+//         
+//         assert_eq!(extract_subject_predicate(SERVICE_ROLLEDBACK), Some(("service","rolledback")));
+//         
+//         assert_eq!(extract_subject_predicate(SERVICE_UPGRADED), Some(("service","upgraded")));
+//         
+//         assert_eq!(extract_subject_predicate(TASKRUN_FINISHED), Some(("taskRun","finished")));
+//         
+//         assert_eq!(extract_subject_predicate(TASKRUN_STARTED), Some(("taskRun","started")));
+//         
+//         assert_eq!(extract_subject_predicate(TESTCASERUN_FINISHED), Some(("testCaseRun","finished")));
+//         
+//         assert_eq!(extract_subject_predicate(TESTCASERUN_QUEUED), Some(("testCaseRun","queued")));
+//         
+//         assert_eq!(extract_subject_predicate(TESTCASERUN_STARTED), Some(("testCaseRun","started")));
+//         
+//         assert_eq!(extract_subject_predicate(TESTOUTPUT_PUBLISHED), Some(("testOutput","published")));
+//         
+//         assert_eq!(extract_subject_predicate(TESTSUITERUN_FINISHED), Some(("testSuiteRun","finished")));
+//         
+//         assert_eq!(extract_subject_predicate(TESTSUITERUN_QUEUED), Some(("testSuiteRun","queued")));
+//         
+//         assert_eq!(extract_subject_predicate(TESTSUITERUN_STARTED), Some(("testSuiteRun","started")));
+//         
+//     }
+// }
\ No newline at end of file
diff --git a/cdevents-sdk/src/generated/repository_created.rs b/cdevents-sdk/src/generated/repository_created.rs
index 7f2ed30..b2d8e60 100644
--- a/cdevents-sdk/src/generated/repository_created.rs
+++ b/cdevents-sdk/src/generated/repository_created.rs
@@ -9,7 +9,7 @@ use serde::{Serialize, Deserialize};
 #[serde(deny_unknown_fields)]
 pub struct Content {
     #[serde(rename = "name",)]
-    pub name: String,
+    pub name: crate::Name,
     #[serde(rename = "owner", default, skip_serializing_if = "Option::is_none",)]
     pub owner: Option<String>,
     #[serde(rename = "url",)]
diff --git a/cdevents-sdk/src/generated/service_deployed.rs b/cdevents-sdk/src/generated/service_deployed.rs
index 1499d5c..b9fe280 100644
--- a/cdevents-sdk/src/generated/service_deployed.rs
+++ b/cdevents-sdk/src/generated/service_deployed.rs
@@ -9,7 +9,7 @@ use serde::{Serialize, Deserialize};
 #[serde(deny_unknown_fields)]
 pub struct Content {
     #[serde(rename = "artifactId",)]
-    pub artifact_id: String,
+    pub artifact_id: crate::Id,
     #[serde(rename = "environment",)]
     pub environment: ContentEnvironment,
 }
@@ -19,7 +19,7 @@ pub struct Content {
 #[serde(deny_unknown_fields)]
 pub struct ContentEnvironment {
     #[serde(rename = "id",)]
-    pub id: String,
+    pub id: crate::Id,
     #[serde(rename = "source", default, skip_serializing_if = "Option::is_none",)]
     pub source: Option<crate::UriReference>,
 }
diff --git a/cdevents-sdk/src/generated/service_published.rs b/cdevents-sdk/src/generated/service_published.rs
index 2740c04..e458076 100644
--- a/cdevents-sdk/src/generated/service_published.rs
+++ b/cdevents-sdk/src/generated/service_published.rs
@@ -17,7 +17,7 @@ pub struct Content {
 #[serde(deny_unknown_fields)]
 pub struct ContentEnvironment {
     #[serde(rename = "id",)]
-    pub id: String,
+    pub id: crate::Id,
     #[serde(rename = "source", default, skip_serializing_if = "Option::is_none",)]
     pub source: Option<crate::UriReference>,
 }
diff --git a/cdevents-sdk/src/generated/service_removed.rs b/cdevents-sdk/src/generated/service_removed.rs
index 2740c04..e458076 100644
--- a/cdevents-sdk/src/generated/service_removed.rs
+++ b/cdevents-sdk/src/generated/service_removed.rs
@@ -17,7 +17,7 @@ pub struct Content {
 #[serde(deny_unknown_fields)]
 pub struct ContentEnvironment {
     #[serde(rename = "id",)]
-    pub id: String,
+    pub id: crate::Id,
     #[serde(rename = "source", default, skip_serializing_if = "Option::is_none",)]
     pub source: Option<crate::UriReference>,
 }
diff --git a/cdevents-sdk/src/generated/service_rolledback.rs b/cdevents-sdk/src/generated/service_rolledback.rs
index 1499d5c..b9fe280 100644
--- a/cdevents-sdk/src/generated/service_rolledback.rs
+++ b/cdevents-sdk/src/generated/service_rolledback.rs
@@ -9,7 +9,7 @@ use serde::{Serialize, Deserialize};
 #[serde(deny_unknown_fields)]
 pub struct Content {
     #[serde(rename = "artifactId",)]
-    pub artifact_id: String,
+    pub artifact_id: crate::Id,
     #[serde(rename = "environment",)]
     pub environment: ContentEnvironment,
 }
@@ -19,7 +19,7 @@ pub struct Content {
 #[serde(deny_unknown_fields)]
 pub struct ContentEnvironment {
     #[serde(rename = "id",)]
-    pub id: String,
+    pub id: crate::Id,
     #[serde(rename = "source", default, skip_serializing_if = "Option::is_none",)]
     pub source: Option<crate::UriReference>,
 }
diff --git a/cdevents-sdk/src/generated/service_upgraded.rs b/cdevents-sdk/src/generated/service_upgraded.rs
index 1499d5c..b9fe280 100644
--- a/cdevents-sdk/src/generated/service_upgraded.rs
+++ b/cdevents-sdk/src/generated/service_upgraded.rs
@@ -9,7 +9,7 @@ use serde::{Serialize, Deserialize};
 #[serde(deny_unknown_fields)]
 pub struct Content {
     #[serde(rename = "artifactId",)]
-    pub artifact_id: String,
+    pub artifact_id: crate::Id,
     #[serde(rename = "environment",)]
     pub environment: ContentEnvironment,
 }
@@ -19,7 +19,7 @@ pub struct Content {
 #[serde(deny_unknown_fields)]
 pub struct ContentEnvironment {
     #[serde(rename = "id",)]
-    pub id: String,
+    pub id: crate::Id,
     #[serde(rename = "source", default, skip_serializing_if = "Option::is_none",)]
     pub source: Option<crate::UriReference>,
 }
diff --git a/cdevents-sdk/src/generated/taskrun_finished.rs b/cdevents-sdk/src/generated/taskrun_finished.rs
index 8603566..d47c3f7 100644
--- a/cdevents-sdk/src/generated/taskrun_finished.rs
+++ b/cdevents-sdk/src/generated/taskrun_finished.rs
@@ -25,7 +25,7 @@ pub struct Content {
 #[serde(deny_unknown_fields)]
 pub struct ContentPipelineRun {
     #[serde(rename = "id",)]
-    pub id: String,
+    pub id: crate::Id,
     #[serde(rename = "source", default, skip_serializing_if = "Option::is_none",)]
     pub source: Option<crate::UriReference>,
 }
diff --git a/cdevents-sdk/src/generated/taskrun_started.rs b/cdevents-sdk/src/generated/taskrun_started.rs
index 3edb228..3f76d68 100644
--- a/cdevents-sdk/src/generated/taskrun_started.rs
+++ b/cdevents-sdk/src/generated/taskrun_started.rs
@@ -21,7 +21,7 @@ pub struct Content {
 #[serde(deny_unknown_fields)]
 pub struct ContentPipelineRun {
     #[serde(rename = "id",)]
-    pub id: String,
+    pub id: crate::Id,
     #[serde(rename = "source", default, skip_serializing_if = "Option::is_none",)]
     pub source: Option<crate::UriReference>,
 }
diff --git a/cdevents-sdk/src/generated/testcaserun_finished.rs b/cdevents-sdk/src/generated/testcaserun_finished.rs
index 6d2051b..c6d4414 100644
--- a/cdevents-sdk/src/generated/testcaserun_finished.rs
+++ b/cdevents-sdk/src/generated/testcaserun_finished.rs
@@ -27,7 +27,7 @@ pub struct Content {
 #[serde(deny_unknown_fields)]
 pub struct ContentTestSuiteRun {
     #[serde(rename = "id",)]
-    pub id: String,
+    pub id: crate::Id,
     #[serde(rename = "source", default, skip_serializing_if = "Option::is_none",)]
     pub source: Option<String>,
 }
@@ -37,7 +37,7 @@ pub struct ContentTestSuiteRun {
 #[serde(deny_unknown_fields)]
 pub struct ContentTestCase {
     #[serde(rename = "id",)]
-    pub id: String,
+    pub id: crate::Id,
     #[serde(rename = "name", default, skip_serializing_if = "Option::is_none",)]
     pub name: Option<String>,
     #[serde(rename = "type", default, skip_serializing_if = "Option::is_none",)]
@@ -53,7 +53,7 @@ pub struct ContentTestCase {
 #[serde(deny_unknown_fields)]
 pub struct ContentEnvironment {
     #[serde(rename = "id",)]
-    pub id: String,
+    pub id: crate::Id,
     #[serde(rename = "source", default, skip_serializing_if = "Option::is_none",)]
     pub source: Option<crate::UriReference>,
 }
diff --git a/cdevents-sdk/src/generated/testcaserun_queued.rs b/cdevents-sdk/src/generated/testcaserun_queued.rs
index c42dfb2..3c5c12c 100644
--- a/cdevents-sdk/src/generated/testcaserun_queued.rs
+++ b/cdevents-sdk/src/generated/testcaserun_queued.rs
@@ -33,7 +33,7 @@ pub struct ContentTrigger {
 #[serde(deny_unknown_fields)]
 pub struct ContentTestSuiteRun {
     #[serde(rename = "id",)]
-    pub id: String,
+    pub id: crate::Id,
     #[serde(rename = "source", default, skip_serializing_if = "Option::is_none",)]
     pub source: Option<String>,
 }
@@ -43,7 +43,7 @@ pub struct ContentTestSuiteRun {
 #[serde(deny_unknown_fields)]
 pub struct ContentTestCase {
     #[serde(rename = "id",)]
-    pub id: String,
+    pub id: crate::Id,
     #[serde(rename = "name", default, skip_serializing_if = "Option::is_none",)]
     pub name: Option<String>,
     #[serde(rename = "type", default, skip_serializing_if = "Option::is_none",)]
@@ -59,7 +59,7 @@ pub struct ContentTestCase {
 #[serde(deny_unknown_fields)]
 pub struct ContentEnvironment {
     #[serde(rename = "id",)]
-    pub id: String,
+    pub id: crate::Id,
     #[serde(rename = "source", default, skip_serializing_if = "Option::is_none",)]
     pub source: Option<crate::UriReference>,
 }
diff --git a/cdevents-sdk/src/generated/testcaserun_started.rs b/cdevents-sdk/src/generated/testcaserun_started.rs
index c42dfb2..3c5c12c 100644
--- a/cdevents-sdk/src/generated/testcaserun_started.rs
+++ b/cdevents-sdk/src/generated/testcaserun_started.rs
@@ -33,7 +33,7 @@ pub struct ContentTrigger {
 #[serde(deny_unknown_fields)]
 pub struct ContentTestSuiteRun {
     #[serde(rename = "id",)]
-    pub id: String,
+    pub id: crate::Id,
     #[serde(rename = "source", default, skip_serializing_if = "Option::is_none",)]
     pub source: Option<String>,
 }
@@ -43,7 +43,7 @@ pub struct ContentTestSuiteRun {
 #[serde(deny_unknown_fields)]
 pub struct ContentTestCase {
     #[serde(rename = "id",)]
-    pub id: String,
+    pub id: crate::Id,
     #[serde(rename = "name", default, skip_serializing_if = "Option::is_none",)]
     pub name: Option<String>,
     #[serde(rename = "type", default, skip_serializing_if = "Option::is_none",)]
@@ -59,7 +59,7 @@ pub struct ContentTestCase {
 #[serde(deny_unknown_fields)]
 pub struct ContentEnvironment {
     #[serde(rename = "id",)]
-    pub id: String,
+    pub id: crate::Id,
     #[serde(rename = "source", default, skip_serializing_if = "Option::is_none",)]
     pub source: Option<crate::UriReference>,
 }
diff --git a/cdevents-sdk/src/generated/testoutput_published.rs b/cdevents-sdk/src/generated/testoutput_published.rs
index 675acbc..b4a146a 100644
--- a/cdevents-sdk/src/generated/testoutput_published.rs
+++ b/cdevents-sdk/src/generated/testoutput_published.rs
@@ -23,7 +23,7 @@ pub struct Content {
 #[serde(deny_unknown_fields)]
 pub struct ContentTestCaseRun {
     #[serde(rename = "id",)]
-    pub id: String,
+    pub id: crate::Id,
     #[serde(rename = "source", default, skip_serializing_if = "Option::is_none",)]
     pub source: Option<String>,
 }
diff --git a/cdevents-sdk/src/generated/testsuiterun_finished.rs b/cdevents-sdk/src/generated/testsuiterun_finished.rs
index a59e593..824bfb6 100644
--- a/cdevents-sdk/src/generated/testsuiterun_finished.rs
+++ b/cdevents-sdk/src/generated/testsuiterun_finished.rs
@@ -25,7 +25,7 @@ pub struct Content {
 #[serde(deny_unknown_fields)]
 pub struct ContentTestSuite {
     #[serde(rename = "id",)]
-    pub id: String,
+    pub id: crate::Id,
     #[serde(rename = "name", default, skip_serializing_if = "Option::is_none",)]
     pub name: Option<String>,
     #[serde(rename = "uri", default, skip_serializing_if = "Option::is_none",)]
@@ -39,7 +39,7 @@ pub struct ContentTestSuite {
 #[serde(deny_unknown_fields)]
 pub struct ContentEnvironment {
     #[serde(rename = "id",)]
-    pub id: String,
+    pub id: crate::Id,
     #[serde(rename = "source", default, skip_serializing_if = "Option::is_none",)]
     pub source: Option<crate::UriReference>,
 }
diff --git a/cdevents-sdk/src/generated/testsuiterun_queued.rs b/cdevents-sdk/src/generated/testsuiterun_queued.rs
index 5fc5ac1..d5cae30 100644
--- a/cdevents-sdk/src/generated/testsuiterun_queued.rs
+++ b/cdevents-sdk/src/generated/testsuiterun_queued.rs
@@ -31,7 +31,7 @@ pub struct ContentTrigger {
 #[serde(deny_unknown_fields)]
 pub struct ContentTestSuite {
     #[serde(rename = "id",)]
-    pub id: String,
+    pub id: crate::Id,
     #[serde(rename = "name", default, skip_serializing_if = "Option::is_none",)]
     pub name: Option<String>,
     #[serde(rename = "url", default, skip_serializing_if = "Option::is_none",)]
@@ -45,7 +45,7 @@ pub struct ContentTestSuite {
 #[serde(deny_unknown_fields)]
 pub struct ContentEnvironment {
     #[serde(rename = "id",)]
-    pub id: String,
+    pub id: crate::Id,
     #[serde(rename = "source", default, skip_serializing_if = "Option::is_none",)]
     pub source: Option<crate::UriReference>,
 }
diff --git a/cdevents-sdk/src/generated/testsuiterun_started.rs b/cdevents-sdk/src/generated/testsuiterun_started.rs
index f735c42..9c27a7d 100644
--- a/cdevents-sdk/src/generated/testsuiterun_started.rs
+++ b/cdevents-sdk/src/generated/testsuiterun_started.rs
@@ -31,7 +31,7 @@ pub struct ContentTrigger {
 #[serde(deny_unknown_fields)]
 pub struct ContentTestSuite {
     #[serde(rename = "id",)]
-    pub id: String,
+    pub id: crate::Id,
     #[serde(rename = "name", default, skip_serializing_if = "Option::is_none",)]
     pub name: Option<String>,
     #[serde(rename = "uri", default, skip_serializing_if = "Option::is_none",)]
@@ -45,7 +45,7 @@ pub struct ContentTestSuite {
 #[serde(deny_unknown_fields)]
 pub struct ContentEnvironment {
     #[serde(rename = "id",)]
-    pub id: String,
+    pub id: crate::Id,
     #[serde(rename = "source", default, skip_serializing_if = "Option::is_none",)]
     pub source: Option<crate::UriReference>,
 }
diff --git a/cdevents-sdk/src/id.rs b/cdevents-sdk/src/id.rs
new file mode 100644
index 0000000..ccebdc6
--- /dev/null
+++ b/cdevents-sdk/src/id.rs
@@ -0,0 +1,88 @@
+use std::{fmt::{Display, Formatter}, str::FromStr};
+
+use serde::{Deserialize, Serialize};
+
+pub type Id = NonEmptyString;
+pub type Name = NonEmptyString;
+
+/// A non-empty string.
+#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Serialize, Deserialize)]
+pub struct NonEmptyString(String);
+
+impl NonEmptyString {
+    pub fn as_str(&self) -> &str {
+        &self.0.as_str()
+    }
+}
+
+impl Default for NonEmptyString {
+    fn default() -> Self {
+        NonEmptyString("00000000-0000-0000-0000-000000000000".to_owned())
+    }
+}
+
+impl From<NonEmptyString> for String {
+    fn from(id: NonEmptyString) -> Self {
+        id.0
+    }
+}
+impl TryFrom<String> for NonEmptyString {
+    type Error = crate::Error;
+
+    fn try_from(value: String) -> Result<Self, Self::Error> {
+        if value.is_empty() {
+            return Err(crate::Error::EmptyString("id"))
+        }
+        Ok(Self(value))
+    }
+}
+
+impl TryFrom<&str> for NonEmptyString {
+    type Error = crate::Error;
+
+    fn try_from(value: &str) -> Result<Self, Self::Error> {
+        if value.is_empty() {
+            return Err(crate::Error::EmptyString("id"))
+        }
+        Ok(Self(value.to_owned()))
+    }
+}
+
+impl FromStr for NonEmptyString {
+    type Err = crate::Error;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        Self::try_from(s)
+    }
+}
+
+impl Display for NonEmptyString {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}", self.0)
+    }
+}
+
+impl From<&NonEmptyString> for String {
+    fn from(id: &NonEmptyString) -> Self {
+        id.0.clone()
+    }
+}
+
+impl AsRef<str> for NonEmptyString {
+    fn as_ref(&self) -> &str {
+        &self.0
+    }
+}
+
+#[cfg(feature = "testkit")]
+impl<> proptest::arbitrary::Arbitrary for NonEmptyString {
+    type Parameters = ();
+    type Strategy = proptest::strategy::BoxedStrategy<Self>;
+
+    fn arbitrary_with(_args: Self::Parameters) -> Self::Strategy {
+        use proptest::prelude::*;
+        "\\PC+".prop_map(|id| 
+            id.try_into().expect("generate valid id")
+        ).boxed()
+    }
+}
\ No newline at end of file
diff --git a/cdevents-sdk/src/lib.rs b/cdevents-sdk/src/lib.rs
index 819f4f8..76887c5 100644
--- a/cdevents-sdk/src/lib.rs
+++ b/cdevents-sdk/src/lib.rs
@@ -8,12 +8,14 @@ mod context;
 pub mod cloudevents;
 mod error;
 mod generated;
+mod id;
 pub(crate) mod serde;
 mod subject;
 mod uri;
 mod uri_reference;
 
 pub use cdevent::*;
+pub use id::*;
 pub(crate) use context::*;
 pub use error::*;
 pub use generated::*;
diff --git a/cdevents-sdk/src/subject.rs b/cdevents-sdk/src/subject.rs
index c58f0f0..f120a4f 100644
--- a/cdevents-sdk/src/subject.rs
+++ b/cdevents-sdk/src/subject.rs
@@ -2,7 +2,7 @@ use std::str::FromStr;
 
 use serde::{Deserialize, Serialize};
 
-use crate::{Content, UriReference};
+use crate::{Content, Id, UriReference};
 
 /// see <https://github.com/cdevents/spec/blob/main/spec.md#cdevent-subject>
 #[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
@@ -11,7 +11,7 @@ pub struct Subject {
     #[serde(rename = "content")]
     content: Content,
     #[serde(rename = "id")]
-    id: String,
+    id: Id,
     #[serde(
         rename = "source",
         default,
@@ -24,13 +24,12 @@ pub struct Subject {
 
 impl Subject {
     /// see <https://github.com/cdevents/spec/blob/main/spec.md#id-subject>
-    pub fn id(&self) -> &str {
+    pub fn id(&self) -> &Id {
         &self.id
     }
 
-    pub fn with_id<T>(mut self, id: T) -> Self
-        where T: Into<String> {
-        self.id = id.into();
+    pub fn with_id(mut self, id: Id) -> Self {
+        self.id = id;
         self
     }
 
@@ -60,7 +59,8 @@ impl Subject {
             id: json["id"]
                 .as_str()
                 .ok_or_else(|| serde::de::Error::missing_field("id"))?
-                .to_string(),
+                .try_into()
+                .map_err(serde::de::Error::custom)?,
             ty: json["type"]
                 .as_str()
                 .ok_or_else(|| serde::de::Error::missing_field("type"))?
@@ -79,10 +79,13 @@ impl Subject {
 impl<T> From<T> for Subject where T: Into<Content>{
     fn from(content: T) -> Self {
         let content = content.into();
-        let ty = content.ty().to_owned();
+        let ty = crate::extract_subject_predicate(content.ty())
+            .map(|(s, _)| s)
+            .unwrap_or("unknown")
+            .to_owned();
         Self {
             content,
-            id: String::new(),
+            id: Id::default(),
             source: None,
             ty,
         }
@@ -97,7 +100,7 @@ impl<> proptest::arbitrary::Arbitrary for Subject {
         use proptest::prelude::*;
         (
             any::<Content>(),
-            "\\PC*",
+            any::<Id>(),
             any::<Option<UriReference>>(),
         ).prop_map(|(content, id, source)| {
             let mut subject = Subject::from(content).with_id(id);
diff --git a/cdevents-sdk/src/uri_reference.rs b/cdevents-sdk/src/uri_reference.rs
index 0af5fb9..53b48d7 100644
--- a/cdevents-sdk/src/uri_reference.rs
+++ b/cdevents-sdk/src/uri_reference.rs
@@ -75,7 +75,7 @@ impl<> proptest::arbitrary::Arbitrary for UriReference {
     fn arbitrary_with(_args: Self::Parameters) -> Self::Strategy {
         use proptest::prelude::*;
         (prop_oneof![
-            "/[a-z_\\-/]*".prop_map(|s| UriReference::from_str(&s).unwrap()),
+            "\\/[a-z_\\-\\/]+".prop_map(|s| UriReference::from_str(&s).unwrap()),
             Just("https://example.com/").prop_map(|s| UriReference::from_str(&s).unwrap()),
         ]).boxed()
     }
diff --git a/cdevents-sdk/tests/specs.rs b/cdevents-sdk/tests/specs.rs
index be3d313..e2b6e70 100644
--- a/cdevents-sdk/tests/specs.rs
+++ b/cdevents-sdk/tests/specs.rs
@@ -32,7 +32,7 @@ fn for_each_example(#[files("../cdevents-spec/examples/*.json")] path: PathBuf)
 
 fn check_against_schema(json: &serde_json::Value, ty: &str) {
     let (subject, predicate) = cdevents_sdk::extract_subject_predicate(ty).expect("valid type: {ty}");
-    let schemapath = format!("../cdevents-spec/schemas/{subject}{predicate}.json");
+    let schemapath = format!("../cdevents-spec/schemas/{subject}{predicate}.json").to_lowercase();
     //TODO optimize to not recompile a previously read schema
     let mut schemas = Schemas::new();
     let mut compiler = Compiler::new();
diff --git a/generator/src/main.rs b/generator/src/main.rs
index 2cf0425..325e56a 100644
--- a/generator/src/main.rs
+++ b/generator/src/main.rs
@@ -46,18 +46,15 @@ fn main() -> Result<()> {
         if let Some(extension) = path.extension() {
             if extension == "json" {
                 let json: Value = serde_json::from_str(&std::fs::read_to_string(&path)?)?;
-                let (rust_module, context_type, code) = generate_variant(&hbs, json)
+                let (variant_info, code) = generate_variant(&hbs, json)
                     .with_context(|| format!("failed to generate variant on {:?}", &path))?;
                 let file = settings
                     .dest
-                    .join(cruet::to_snake_case(&rust_module))
+                    .join(cruet::to_snake_case(&variant_info.rust_module))
                     .with_extension("rs");
                 //TODO use a formatter like https://crates.io/crates/prettyplease?
                 fs::write(file, code)?;
-                variants.push(VariantInfo {
-                    context_type,
-                    rust_module,
-                });
+                variants.push(variant_info);
             }
         }
     }
@@ -71,7 +68,7 @@ fn main() -> Result<()> {
     Ok(())
 }
 
-fn generate_variant(hbs: &Handlebars, jsonschema: Value) -> Result<(String, String, String)> {
+fn generate_variant(hbs: &Handlebars, jsonschema: Value) -> Result<(VariantInfo, String)> {
     // let id = jsonschema["$id"]
     //     .as_str()
     //     .ok_or(anyhow!("$id not found or not a string"))
@@ -90,11 +87,23 @@ fn generate_variant(hbs: &Handlebars, jsonschema: Value) -> Result<(String, Stri
         .to_string();
 
     let fragments = context_type.split('.').collect::<Vec<_>>();
-    let module_name = format!("{}_{}", fragments[2], fragments[3]).to_snake_case();
+    let rust_module = format!("{}_{}", fragments[2], fragments[3]).to_snake_case();
+    let predicate = fragments[3].to_owned();
+    // due to inconstency in case/format the subject could be not be extracted from the context.type (ty), jsonshema $id, spec filename (shema, examples)
+    let subject = jsonschema["properties"]["subject"]["properties"]["type"]["default"]
+        .as_str()
+        .unwrap_or_default()
+        .to_string();
 
     let data = build_data_for_variants(jsonschema);
     let code = hbs.render("variant", &data)?;
-    Ok((module_name.to_string(), context_type, code))
+    let variant_info = VariantInfo {
+        context_type,
+        rust_module,
+        subject,
+        predicate,
+    };
+    Ok((variant_info, code))
 }
 
 fn generate_module(hbs: &Handlebars, variants: &[VariantInfo]) -> Result<(String, String)> {
@@ -133,6 +142,8 @@ struct TypeInfo {
 struct VariantInfo {
     context_type: String,
     rust_module: String,
+    subject: String,
+    predicate: String,
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
@@ -183,12 +194,22 @@ fn collect_structs(
             //     type_declaration: "http::Uri".to_string(),
             //     serde_with: Some("crate::serde::uri".to_string()),
             // },
-            //TODO manage enum
             _ => match json_definition["enum"].as_array() {
-                None => TypeInfo {
-                    type_declaration: "String".to_string(),
-                    ..Default::default()
-                },
+                None => {
+                    let type_declaration =
+                        match (field_names.last(), json_definition["minLength"].as_i64()) {
+                            (Some(&"id"), _) => "crate::Id",
+                            (Some(&"name"), Some(1)) => "crate::Name",
+                            (Some(x), Some(1)) if x.ends_with("Id") => "crate::Id",
+                            (Some(x), Some(1)) if x.ends_with("Name") => "crate::Name",
+                            _ => "String",
+                        }
+                        .to_string();
+                    TypeInfo {
+                        type_declaration,
+                        ..Default::default()
+                    }
+                }
                 Some(values) => {
                     let default_value = json_definition["default"].as_str();
                     let values = values
diff --git a/generator/templates/mod.hbs b/generator/templates/mod.hbs
index e8b2625..51f4665 100644
--- a/generator/templates/mod.hbs
+++ b/generator/templates/mod.hbs
@@ -45,14 +45,32 @@ impl Content {
         }
     }
 
-    pub fn subject_predicate(&self) -> (&'static str, &'static str){
-        let mut split = self.ty().split('.');
-        (
-            split.nth(2).expect("fargment 2 of ty should always exists"),
-            split.nth(3).expect("fargment 3 of ty should always exists")
-        )
+    pub fn subject(&self) -> &'static str {
+        match self {
+            {{#each variants }}
+            Self::{{to_class_case this.rust_module}}(_) => "{{ this.subject }}",
+            {{/each}}
+        }
     }
 
+    pub fn predicate(&self) -> &'static str {
+        match self {
+            {{#each variants }}
+            Self::{{to_class_case this.rust_module}}(_) => "{{ this.predicate }}",
+            {{/each}}
+        }
+    }
+}
+
+// due to inconstency in case/format the subject could be not be extracted from the context.type (ty), jsonshema $id, spec filename (shema, examples)
+pub fn extract_subject_predicate(ty: &str) -> Option<(&str, &str)>{
+    // let mut split = ty.split('.');
+    match ty {
+        {{#each variants }}
+        {{to_screaming_snake_case this.rust_module}} => Some(("{{ this.subject }}", "{{ this.predicate }}")),
+        {{/each}}
+        _ => None,
+    }
 }
 
 {{#each variants }}
@@ -77,3 +95,15 @@ impl<> proptest::arbitrary::Arbitrary for Content {
         ].boxed()
     }
 }
+
+// #[cfg(test)]
+// mod tests {
+//     use super::*;
+// 
+//     #[test]
+//     fn test_true() {
+//         {{#each variants }}
+//         assert_eq!(extract_subject_predicate({{to_screaming_snake_case this.rust_module}}), Some(("{{ this.subject }}","{{ this.predicate }}")));
+//         {{/each}}
+//     }
+// }
\ No newline at end of file