diff --git a/crates/yuck/src/config/attr_value.rs b/crates/yuck/src/config/attr_value.rs
index 7f951248..1067eb6e 100644
--- a/crates/yuck/src/config/attr_value.rs
+++ b/crates/yuck/src/config/attr_value.rs
@@ -27,6 +27,7 @@ impl AttrValue {
     }
 }
 
+/// an action as it is provided by the user. These actions contain Expressions which may reference variables.
 #[derive(Debug, Clone, Eq, PartialEq)]
 pub enum Action {
     Update(VarName, SimplExpr),
@@ -57,6 +58,8 @@ impl Action {
     }
 }
 
+/// an action ready for execution.
+/// The expressions in this struct may only reference the variable "event", and _must_ be fully resolved otherwise.
 #[derive(Debug, Clone, Eq, PartialEq)]
 pub enum ExecutableAction {
     Update(VarName, SimplExpr),