Sub form validations

Hi All:
I am pretty new to this stuff, but need to figure out how control data flow
in a form with a bunch of tabbed sub forms. I will try to see if I can make
this make sense:
We have a foirm with a bunch of tabbed sub forms used for dataentry. We need
to control thins so that if someone enters data in a field of one of the sub
forms, they cannot exit the form without clicking the save button and
therefor cannot click on another tab in the master form until the data is
saved. For instance, tab a calls for first name and last name. Once data is
entered into either field, the user cannot click on tab b which would be for
credit limit until the data in tab a has been saved.

Hope this post makes some sense to someone

TIF

--
SteveG