docs: function(category, type, name, lang)
      {
          if (typeof name === 'undefined') {
             name = '';
          }
          if (typeof lang === 'undefined') {
             lang = '';
          }
          for (var i=0; i<this._identities.length; i++)
          {
              if (this._identities[i].category == category &&
                  this._identities[i].type == type &&
                  this._identities[i].name == name &&
                  this._identities[i].lang == lang)
              {
                  return false;
              }
          }
          this._identities.push({category: category, type: type, name: name, lang: lang});
          return true;
      }