no version of FileMaker can create a field with a script or a calculation...
but it can display a field ( or more than one ) that is in the DB, but is hide.
There are many tecniques to do such thing but the powerfull one remains what was named "portal trick".
You need to:
1) create those two fields ( Create date and Expire date )
2) create a calculation field result text ( name it Yes ) with calc: Case( yourFieldWithList = "Yes" ; "Yes" )
3) create a self-relationship:
a) while in the relationship graph you have to duplicate the main table ( really you'll see 2 occurrences of the same table ) that automatically will have the same name of the DB with a 2 suffix
b) create a line that start from Main::yourFieldWithList and stop to Main 2::Yes
4) While in layout mode, insert the field Main 2::create date and Main 2::Expire date into a single line portal showing records of Main 2
This is all.
When you'll set the field yourFieldWithList to "No" you will not see those field; on the contrary you will see and edit those fields.
I think what you are wanting can be done with script triggers, but that was just introduced in Filemaker Pro 10.
ex. - a dialog box script that is triggered when you enter or modify the field.
unsure how to trigger this in a pre-10 solution.
Thanks for all replies