Task Number Format Validation

Summary:

How can we restrict the length and types of characters used when entering a task number? In our case, we want to restrict to a 6-character alphanumeric-only value.

Content (required):

In the Oracle PPM Task setup, is there a way to apply a validation to the task number field such that it will block the saving of the new task if it does not match a regular expression value?

For other fields on the project, it seems we can do this via page composer. But the task fields do not appear to be available on the ProjectRestVO that screen exposes.