code: function isValidIdentifierCharacter(ch) {
    if (!ch) {
      return false
    }
  
    return (
      0x2d == code(ch) || // '-'
      0x2e == code(ch) || // '.'
      0x3a == code(ch) || // ':'
      inRange(code(ch), 0x30, 0x39) || // 0-9 (DIGIT)
      inRange(code(ch), 0x61, 0x7a) || // a-z (ALPHA)
      inRange(code(ch), 0x41, 0x5a)    // A-Z (ALPHA)
    )
  }
docs: specific-idstring  = idstring *( ":" idstring ) idstring           = 1*idchar idchar             = ALPHA / DIGIT / "." / "-"