function isEmpty(s)
{   return ((s == null) || (s.length == 0))
}

function isRequired( field )
{
  if (field.getAttribute('req')=="yes")
     return true
  else
    return false
}

function validateForm ( theForm )
{
	var result = true
   for ( i=0 ; i < theForm.elements.length ; i++)
   {
      var theField = theForm.elements[ i ];

      if ( isEmpty(theField.value) && isRequired(theField) )
      {
      	if ( ! ( theField.className.indexOf( "error" ) > 0 )  ) 
    		changeStyle( theField , theField.className + "error" );
    		
         result = false;
      }
   }
   return result;
}