[AccessD] Just Curious

I have a sub-form on a form.  Most of the time when I make a change to any
form in this app and say Save, it asks to save this sub-form as well as if
it had been modified.
 
Now this form (and sub-form) are opened but invisible since it takes a long
time to load. Don't know if that has anything to do with it.

It's not a problem, I just click Save All.  But I'm curious as to why this
particular sub-form comes up as needing to be saved when I modify any other
form in the app.

MTIA

Rocky