! XML rule
define XMLns [AsciiLetter [AsciiLetter|Digit|%-]* (%: AsciiLetter [AsciiLetter|Digit|%-]*)] .o. Caseinsensitive;
read regex [
  "<" [
      [
        XMLns
        [WS+ XMLns WS*
          (%= WS*
            [[%" [? - %" - %>]+ %"] | [%' [? - %' - %>]+ %']]
          )
        ]*
        (WS* "/")   
      ]
      |
      [
        "/" XMLns
      ]
    ] WS* ">"
].u;