#include <MsgBoxConstants.au3> ; to declare the Constants of MsgBox
Local $sRegex = "(?m),?[ ]*([^',\n]*(?:'[^'\n]*'[^',\n]*)*)"
Local $sString = "21, 2, '23.5R25 ETADT', 'description, with a comma'" & @CRLF & _
"22, 1, '26.5R25 ETADT', 'Description without a comma'" & @CRLF & _
"23, 5, '20.5R20.5', 'Another description with ; semicolumn'"
Local $sSubst = "\1\t"
Local $sResult = StringRegExpReplace($sString, $sRegex, $sSubst)
MsgBox($MB_SYSTEMMODAL, "Result", $sResult)
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for AutoIt, please visit: https://www.autoitscript.com/autoit3/docs/functions/StringRegExp.htm