There were some great discussions at FileMaker Bootcamp (thank you Russell Kohn, Lee Lukehart, Allen Imbarrato, and Bob Majors) along with a spirited discussion of naming conventions.
Jonn Howell proposed these conventions (where CON is his abbreviation for “Contacts”)…
___kp_CON primary key
__kf_CON foreign key
_kg_selected_CON global key
What do you think of that?