In the VALID event of the control you could build a routine that processes each character in THIS.VALUE and determines if it is in the set of allowable characters.
lReturnValue = .t.
for j = 1 to len(this.value)
ch = substr(this.value,j,1)
if not upper(ch) $ "ABCDEFGHIJKLMNOPQRSTUVWXYZ "
lReturnValue = .f.
exit
endif
endfor
return lReturnValue
Don