diff --git a/lobster/tools/trlc/requirements.rsl b/lobster/tools/trlc/requirements.rsl
new file mode 100644
index 00000000..ddbdd052
--- /dev/null
+++ b/lobster/tools/trlc/requirements.rsl
@@ -0,0 +1,9 @@
+package trlc_req
+
+type Tool_Requirement {
+  description '''
+    The content of the requirement.
+    A tool requirement describes the behaviour of a lobster tool from the point of view of the user.
+    It does not describe implementation details.
+  ''' String
+}
\ No newline at end of file
diff --git a/lobster/tools/trlc/requirements.trlc b/lobster/tools/trlc/requirements.trlc
new file mode 100644
index 00000000..80661a65
--- /dev/null
+++ b/lobster/tools/trlc/requirements.trlc
@@ -0,0 +1,8 @@
+package trlc_req
+
+Tool_Requirement OUTPUT_FILE {
+    description = '''
+      If a output file is specified as command line argument, then the output must be written into that file.
+      Otherwise, the output shall be written to 'trlc.lobster'.
+    '''
+}
\ No newline at end of file
diff --git a/lobster/tools/trlc/trlc.py b/lobster/tools/trlc/trlc.py
index a1c02dc8..4dbf65b6 100644
--- a/lobster/tools/trlc/trlc.py
+++ b/lobster/tools/trlc/trlc.py
@@ -368,6 +368,7 @@ def main():
                     help=("name of lobster-trlc config file, "
                           "by default %(default)s"),
                     default="lobster-trlc.conf")
+    # lobster-trace: trlc_req.OUTPUT_FILE
     ap.add_argument("--out",
                     help=("name of output file, "
                           "by default %(default)s"),
@@ -438,6 +439,7 @@ def main():
         return 1
 
     with open(options.out, "w", encoding="UTF-8") as fd:
+        # lobster-trace: trlc_req.OUTPUT_FILE
         lobster_write(fd        = fd,
                       kind      = Requirement,
                       generator = "lobster-trlc",