#include <MsgBoxConstants.au3> ; to declare the Constants of MsgBox
Local $sRegex = "(?s)(>)()(<\/)"
Local $sString = " <file> " & @CRLF & _
" <fileType>Mezza</fileType>" & @CRLF & _
" <fileName></fileName>" & @CRLF & _
" <any_other_tag></any_other_tag>" & @CRLF & _
" <any_other_tag> </any_other_tag>" & @CRLF & _
" <segments>0000</segments>" & @CRLF & _
" </file>"
Local $sSubst = "\1[!] value does not exist!\3"
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