Doubt in email Validation....

That is a list of the characters you want to keep from the email adress when comparing to the original content.

Keepchar examples:

keepchar('bonjour','jour') = 'bon'

keepchar('Abcd123','123') = '123'

purgechar is the opposite, it define which characters should be removed :

purgechar('bonjour','jour') = 'jour'

purgechar('Abcd123','123') = 'Abcd'

Have a look in the help files. They have often good examples. As a  beginner though it is dificult to know "what" to search for. But if you search for "string functions" in the help, you will find a lot of useful functions.

Robert