Nice shot. However, exactly your case ("whatever") showed a problem. It could be repaired by decreasing lnBase with 1 and increasing lnRest with 1. Here's the testcode:

create cursor c_sys2007 ( theNumber i, theString c(10) )
for n = 1 to 99999
	lnval = n
	lcLetters = "ABCDEFGHIJKLMNOPQRSTUVWXY"
	lcCharList = lcLetters + LOWER(lcLetters)
	lnBase = LEN(lcCharList) - 1
	lcVal = ""
	DO WHILE lnVal > 0
		lnRest = lnVal % lnBase
		lnVal = INT( lnVal / lnBase)
		lcVal =  SUBSTR( lcCharList, lnRest + 1, 1 ) + lcVal
	ENDDO
	insert into c_sys2007 values ( n, lcVal )
next

browse title "Raw result"

select cnt(*) as _cnt, theString from c_sys2007 order by 2 group by 2 into cursor c_sys2007a
browse title "Occurence of each string - Desc - Column 1 should have no other value than 1"

select len(alltrim(thestring)) as theLen from c_sys2007a order by 1 desc into cursor c_sys2007b
select dist theLen from c_sys2007b order by 1 desc into cursor c_sys2007c
browse title "Distinct of lengths"

I think I'll gonna use a variation. lcCharlist will be lcLetters only, in order to have only upper case in the outcome. And I want the string to be four positions always. That can be accomplished by reserving the Z, so by decreasing lcLetters with 1 and doing padr() with the Z.

Problem solved. Thanks Sergey. Did you write this today?

>

>CLEAR
>lnVal = INT(VAL(SYS(2007, "whatever")))
>
>lcLetters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
>lcCharList = lcLetters + LOWER(lcLetters)
>lnBase = LEN(lcCharList)
>lcVal = ""
>DO WHILE lnVal > 0
>	lnRest = lnVal % lnBase
>	lnVal = INT( lnVal / lnBase)
>	lcVal =  SUBSTR(lcCharList, lnRest,1) + lcVal
>ENDDO
>? lcVal
>

>>
>>The length of sys(2007) is 5 numbers. I'd like to convert this into a character string of alphabetic letters (A-Z), in order to get rid of some positions. I can write the algorithm, but perhaps someone else already wrote one?!