code: function addLeafSymbol(sId) {
  		// Note: this function is executed at load time only!
  		mFilterParserSymbols[sId] = {
  			lbp : 0,
  			nud : function (oToken) {
  				oToken.precedence = 99; // prevent it from being enclosed in brackets
  				return oToken;
  			}
  		};
  	}
docs: Adds a leaf symbol to mFilterParserSymbols.
  
  @param {string} sId The token ID