>I don't remeber where I found the below code, but thanks to the original author. I have a coupla questions on it, though.
> 1. What is this Windows library based on (NIC, hd id, etc)?
> 2. How do I know these are "really" unique across time & space?
>
>*Create a Universally Unique ID
>*Adapted from the book Visual FoxPro 5
>*Enterprise Development One of the most
>*common problems faced with developers
>*is a method of creating unique keys. This
>*is where a UUID (Univerally Unique ID)
>*comes in. UUID's are a IEEE standard
>*method of generating Universally Unique
>*values. What this means is the values
>*returned are unique across time and
>*space. The code below calls the Windows API
>*and returns a UUID.
>
>
>Function getUUID
>
>*-- The UUID Create function is in this library
>DECLARE Integer UuidCreate IN C:\Windows\System\RPCRT4.DLL ;
> String @ UUID && note that mixed case is important for UuidCreate
>
>*-- Create a buffer
>lcUUID = Space(16)
>
>*-- generate the key
>=UUIDCreate(@lcUUID)
>
>*-- Convert the binaries to hex values
>lcPart1 = BinAsHex(Substr(lcUUID,1,4))
>lcPart2 = BinAsHex(Substr(lcUUID,5,4))
>lcPart3 = BinAsHex(Substr(lcUUID,8,4))
>lcPart4 = BinAsHex(Substr(lcUUID,13,4))
>
>Local lcRetVal
>lcRetVal = lcPart1 + lcPart2 + lcPart3 + lcPart4
>Return Left(lcRetVal,8) + "-" + substr(lcRetVal,9,4) + "-" + substr(lcRetVal,13,4) + "-" + ;
> substr(lcRetVal,17,4) + "-" + Right(lcRetVal,12)
>
>PROCEDURE binashex
>Parameters lcBin
>* translates a binary string into character string of hex
>LOCAL lcChars, lnBin
>
>lcChars = ""
>FOR lnDigit = 1 TO LEN(lcBin)
> lnBin = ASC(SUBSTR(lcBin, lnDigit, 1))
> lcChars = lcChars + Hex2Char(INT(lnBin/16)) + ;
> Hex2Char(MOD(lnBin,16))
>ENDFOR
>
>RETURN(lcChars)
>
>PROCEDURE hex2char
>* takes a hex digit value and returns a character from 0-9 & A-F
>LPARAMETERS lnHex
>DO CASE
> CASE BETWEEN(lnHex,0,9)
> lnAsc = 48 + lnHex
> CASE BETWEEN(lnHex,10,15)
> lnAsc = 65 + lnHex - 10
>ENDCASE
>RETURN(CHR(lnAsc))


Microsoft says the values will never be duplicated. UUID is another name for GUID. However, do you really want a 16 byte ID when a 4 byte Integer will work?