#include <MsgBoxConstants.au3> ; to declare the Constants of MsgBox
Local $sRegex = "(?m)^([a-zA-Z]{2,4})(_)(\d{2})_(0*)(\d+)(_.+)?"
Local $sString = "BTS_33_198_D" & @CRLF & _
"PL_14_015" & @CRLF & _
""
Local $sSubst = "\1\\\2\3\\_%\5%"
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