docs: function ( sData )
  		{
  			/* Allow zero length strings as a number */
  			if ( typeof sData === 'number' )
  			{
  				return 'numeric';
  			}
  			else if ( typeof sData !== 'string' )
  			{
  				return null;
  			}
  			
  			var sValidFirstChars = "0123456789-";
  			var sValidChars = "0123456789.";
  			var Char;
  			var bDecimal = false;
  			
  			/* Check for a valid first char (no period and allow negatives) */
  			Char = sData.charAt(0); 
  			if (sValidFirstChars.indexOf(Char) == -1) 
  			{
  				return null;
  			}
  			
  			/* Check all the other characters are valid */
  			for ( var i=1 ; i<sData.length ; i++ ) 
  			{
  				Char = sData.charAt(i); 
  				if (sValidChars.indexOf(Char) == -1) 
  				{
  					return null;
  				}
  				
  				/* Only allowed one decimal place... */
  				if ( Char == "." )
  				{
  					if ( bDecimal )
  					{
  						return null;
  					}
  					bDecimal = true;
  				}
  			}
  			
  			return 'numeric';
  		}