FOR i=1 TO LEN(ALLT(THISFORM.txtnic.VALUE)) IF !INLIST(SUBSTR(ALLT(THISFORM.txtnic.VALUE),i,1), '1','2','3','4','5','6','7','8','9','0','A','B','C','D','E','F') warningmessage=warningmessage+CHR(13)+'Invalid NIC address. (Non hex digit)'+' "'+SUBSTR(ALLT(THISFORM.txtnic.VALUE),i,1)+'"' THISFORM.txtnic.SETFOCUS oktosave=.F. ENDIF ENDFORbut im not sure if you can loop through each character. Any help is appreciated.