Call popup Form ID with multiple fields

[Alberto]

Hi, I have a table wich unique ID index is ID,IDFILE,INSTANCE (3 fields)
How to set it in the popup call?
Please see image.

[Bruce]

are you trying to call this popup as a lookup?

[Alberto]

No its a button that calls a form as a popup, change mode, but how to set the unique key?

[Bruce]

I'm not sure if it's possible, but if you make an example I'll take a look.

cheers
Bruce

[Alberto]

May be Im not clear enought, please see the attached image, its the Onclick Tab of a button that is calling a form, no matter it is in popup form or not.
Lets say I need to change the record, then I check "Include Action" and select "Change" Action.
What do I have to type in Table Id Value?
My guess is that it is for the unique key for the form to get the record to change.
Then what if the unique key has multiple fields?