PR['registerLangHandler'](
  PR['createSimpleLexer'](
    [
      // Whitespace.
      [PR['PR_PLAIN'], /^[\t\n\r \xA0]+/, null, '\t\n\r \xA0']
    ],
    [
      // Multi-line comments
      [PR['PR_COMMENT'], /#\!(\#(?!\!)|[^!])*\!\#/i],
      // Single-line comments.
      [PR['PR_COMMENT'], /(##).*\n?/i],
      // xml comments
      [PR['PR_COMMENT'],     /^<\!--[\s\S]*?(?:-\->|$)/],
      // General keywords.
      [PR['PR_KEYWORD'], /(?:#set|#foreach|#end|#if|#elseif|#else|#parse|#macro|#stop|#include)/i],
      // Keywords for constants.
      [PR['PR_KEYWORD'], /^\b(?:false|null|true)\b/i],
      // Multiline strings, single- and double-quoted.
      [PR['PR_STRING'], /^r?[\']{3}[\s|\S]*?[^\\][\']{3}/],
      [PR['PR_STRING'], /^r?[\"]{3}[\s|\S]*?[^\\][\"]{3}/],
      // Normal and raw strings, single- and double-quoted.
      [PR['PR_STRING'], /^r?\'(\'|(?:[^\n\r\f])*?[^\\]\')/],
      [PR['PR_STRING'], /^r?\"(\"|(?:[^\n\r\f])*?[^\\]\")/],
      // Types are capitalized by convention.
      // Identifiers.
      [PR['PR_PLAIN'], /^[a-z_$][a-z0-9_]*/i],
      // Decimal numbers.
      [PR['PR_LITERAL'], /^\b\d+(?:\.\d*)?(?:e[+-]?\d+)?/i],
      [PR['PR_LITERAL'], /^\b\.\d+(?:e[+-]?\d+)?/i],
	  ['lang-in.tag',  /^(<\/?[a-z][^<>]*>)/i]	
    ]),
  ['vm']);