f the formal grammar.
         
      </p>
      
      <div class="note">
         
         <p>The concept of "well formed" is close to what is required here. However, exact parsing
            requirements vary amongst markup languages, and most non XML-based languages do not
            explicitly define requirements for well formedness. Therefore, it was necessary to
            be more explicit in the success criterion in order to be generally applicable to markup
            languages. Because the te