Restrict Numbers in any String

static void JobX(Args _args)
{
boolean ret;
#define.alphabets('ABCDEFGHIJKLMNOPQRSTUVWXYZ')
str     Str1;    //Declare your Field here
;
Str1 = "efrt0211"; // Define the case here
if((strkeep(substr(Str1, 1, strlen(Str1)), #alphabets)  != substr(Str1, 1, strlen(Str1))))
{
ret = checkFailed("You cannot enter other than alphabets");
}
else
{
info (strfmt("%1",str1));
}
}