function ValidateForm(form)
{
	if(form.area.value=="")
   { 
      alert('Please enter an area of paving in square metres.') 
      form.area.focus(); 
      return false; 
   }  
          var numericExpression = /^[0-9]+$/;
	if(form.area.value.match(numericExpression))
   { 
      return true; 
	  }else{
		alert('You must enter ONLY NUMBERS for the area of paving.') 
      form.area.focus(); 
		return false;
	}

 return false;
 }