editing master list of data merge fields

Can you please tell me where I go in the system to edit the master list of data merge fields that can be used in PDF and other documents?

I don’t think there any such list only in place. I didn’t check, but I’m almost certain this is build dynamically from the Vardefs of each module. These describe the data structures used by SuiteCRM, you can look it up in the Developer Guide.

Maybe if you tell me what you’re trying to achieve I can suggest an alternative approach.