function IsNumeric(sText)

{
   var ValidChars = "0123456789.+-() ";
   var IsNumber=false;
   var Char;
  
   for (i = 0; i < sText.length && IsNumber == false; i++) 
      { 
      Char = sText.charAt(i); 
      if (ValidChars.indexOf(Char) == -1) 
         {
         IsNumber = true;
         }
      }
   return IsNumber;
   
   }