I have a very large library of code in an XLA. The code inside can be
classified into three categories:

1) global code for things like returning dates, finding sheets, etc.
2) code that is used interactively by the end-users
3) code that is used only by me to make sheets for the end users

A major problem with the current system is that the code is required
by anyone that opens any of the sheets. When this happens, the first
user to open gets a lock on the XLA. This locks me out of the code so
I can't save changes.

I would like to split the code into three libraries. The obvious way
would be do make three XLAs, but then you run into the problem of
calling code across them -- especially the "global" code that is used
all over the place. Someone suggested I could avoid this using
References, but I never figured that out.

I'm sure someone else has faced this problem before, any advice?

Maury