Jay,

Thanks. Actually, on the way home I figured this out. I guess, I just hadn't enough time at the moment I needed to solve this problem. Since X could be either digit or letter, I first do the same replacement as in the code, then I can substitute letters with 9 too :) So, instead of X I would place 9 in lcMask

>>Hi everybody,
>>
>>I have this peice of code:

>>local lcMask,  lcDigits, lcLetters, lcAPNUniform
>>lcMask = "999999X-X999999X-X999999XX-XX999999X"
>>lcApn = padr(ltrim(m.tcAPN),36)
>>lcDigits = "0123456789"
>>lcLetters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ "
>>lcAPNUniform = chrtran(m.lcAPN, m.lcDigits+m.lcLetters, ;
>>	replicate("9", 10)+ replicate("X", 27))

>>
>>X in the mask can mean either digit or letter. However, if I have digit in, say, 7th position, my lcAPNUniform doesn't put X there, it puts 9, so I mark this APN as bad, while I should not. I could not think about anything except for checking each position, where X as allowed. Is there a more effective way?
>>
>>Thanks a lot in advance.
>
>Nadya --
>
>You've probably implemented your other solution by now.
>
>As you well noted, it seems like you need to use lower level string search functions in order to accomplish what you want.
>
>The TRANSFORM function, though, allows us to extract specific letters at specific positions, if we have a mask which has X's in the positions we want a character, and blanks where we don't.
>
>So, we need to generate the submasks for each specific data type in the mask. The RetFormat function replaces all positions in a mask string with a space for non-matching characters, and with an X for matching characters. That function saves the time (and ensures accuracy) for setting up the various submasks needed.
>
>The llValid assignment expression reproduces what you're already doing (seeing if the mask and converted string are equal) with one significant exception. Because we're using a mask, rather than comparing literals, we can supply multiple "filters" through CHRTRAN, to eliminate any variation of the characters we need.
>
>I tried this out and it gave the results that I think you're expecting.
>
>Merry Christmas!
>
> Jay
>
>
>

>*	Returns a string of X's, to be used as a mask in a TRANSFORM statement
>*	to return X's in the position of the passed symbol in the passed mask.
>
>
>FUNCTION	RetFormat
>LPARAMETER		tcMask, tcSymbol
>LOCAL			lcFormat
>
>#DEFINE   SYMBOL_NOT_IN_STRING    "~"
>
>
>	lcFormat = CHRTRAN (tcMask, CHRTRAN (tcMask, tcSymbol, SYMBOL_NOT_IN_STRING), SPACE (LEN (tcMask)))
>	lcFormat = STRTRAN (lcFormat, tcSymbol, "X")
>
>	RETURN	lcFormat
>ENDFUNC
>
>PROCEDURE	SetupPatternMatch
>LOCAL	lcDigits, lcLetters, lcMask, lcANMask, lcNMask, lcSepMask, lcPattern, lcValid, ;
>	lcSep, lcSepBlank, llValid
>
>	lcDigits = "0123456789"
>	lcDigitsBlank = SPACE (10)
>	lcLetters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ "
>	lcLettersBlank = SPACE (27)
>	lcSep = "-"
>	lcSepBlank = SPACE (1)
>
>	lcMask = "X9-9X"
>	lcANMask = RetFormat (lcMask, "X")
>	lcNMask = RetFormat (lcMask, "9")
>	lcSepMask = RetFormat (lcMask, "-")
>
>	lcPattern = "A8-7B"    &&  .T.
>*	lcPattern = "A8-BB"    &&  .F.
>*	lcPattern = "A8-77"    &&  .T. !!!
>
>
>	llValid = EMPTY (CHRTRAN (TRANSFORM (lcPattern, lcNMask), lcDigits, lcDigitsBlank)) ;
>		AND EMPTY (CHRTRAN (TRANSFORM (lcPattern, lcSepMask), lcSep, lcSepBlank)) ;
>		AND (EMPTY (CHRTRAN (CHRTRAN (TRANSFORM (lcPattern, lcANMask), lcLetters, lcLettersBlank),  ;
>			lcDigits, lcDigitsBlank)))
>	WAIT WINDOW TRANSFORM (llValid)
>
>ENDPROC
>