Fumei....

I can't see how to make things clearer!

I accept that I cannot (as suspected) interrogate a system variable to determine how Word was invoked.

If, in Document_Open the VBA takes control of the User's options and does not allow the User the option of entering the VB Editor, then there is no easy way for the Developer to access the VBE by simply opening the document. (In the processes I am developing the document is created solely from User input to the various Userforms.)

Surely, if you've worked in a Production environment you must be aware that as Business needs change, it is often necessary to amend Production code. It is also normal during a development cycle to have User Acceptance Testing of different levels of functionality before the final code is produced and approved. Therefore amendments to code previously deemed to be final (in however temporary a sense) are necessary.
I was simply looking for an easier way to maintain two versions of the doment; a "closed" version for the Users, and an "open" version for further development.