When do field validations occur?

[lawaid]

Two questions from my experience playing with FMP7--I am a new FMP developer by the way:

Q. The Moyer document of hints & tricks (MOYEC49.pdf) claims that field validation occurs AFTER auto-enter calculations, but my experiments seem to indicate otherwise. Who is right?

Q. What's the behavioral difference between validate data entry "Always" and "Only on data entry" for field validations? If I choose Always, when do the validations occur?

I have a third question unrelated to validation posted in the FMP3 message board too, but I'll throw it out here as well--why would a developer working with FMP3 choose to use GetAsNumber("") to indicate false in number fields acting as flags?

Thanks for all your input.