From the Gen r8.5 (and r8.6) documentation, it contains example steps to use the CALL EXTERNAL statement. At the end of those steps, it contains the following notes:
- If the action diagram has any statements other than NOTE statements in it, the menu option for adding a Call External statement is disabled.
- You cannot add a CALL EXTERNAL statement in an action diagram that has local or entity action views. To add a CALL EXTERNAL statement, the action diagram must only have import and export views.
- After adding a CALL EXTERNAL statement, the only statements that are allowed to be added in that action diagram are NOTEs and blank lines.
- CALL EXTERNAL statement is valid for all languages that are supported by CA Gen except COBOL.
- CALL EXTERNAL statement does not support NonStop operating system.
Here is the document reference link: https://docops.ca.com/ca-gen/8-5/en/developing/designing/using-toolset/working-with-toolset/use-action-diagram/assignment-action-statements/add-a-call-external-statement