<!--
function checkNumber(numStr, fieldName)
{
	msg = fieldName + " field has invalid data: " + numStr.value;
	str = numStr.value;
	for (var i=0; i < str.length; i++)
	{
		var ch = str.substring(i,i+1);
		if ( (ch < "0" || ch > "9") && ch != '.' )
		{
			alert(msg);
			return false;
		}
	}
	return true;
}

function computeWeightForm(weightform)
{
	// if both forms empty - error
	if ( (weightform.kilogram.value == null || 
            weightform.kilogram.value.length == 0) &&
           (weightform.pound.value == null ||
            weightform.pound.value.length == 0) )
	{
		alert("Both fields empty.");
		return;
	}

	// if both forms filled error
	if ( (weightform.kilogram.value != null &&
		weightform.kilogram.value.length > 0) &&
		(weightform.pound.value != null &&
		 weightform.pound.value.length > 0) )
	{
		alert("Error: both fields have data.");
		return;
	}

	// calculate kilograms
	if ( (weightform.kilogram.value == null ||
		weightform.kilogram.value.length == 0) &&
		(weightform.pound.value != null &&
		 weightform.pound.value.length > 0) )
      {
		if (checkNumber(weightform.pound,"Pounds"))
		{
			weightform.kilogram.value = (weightform.pound.value * 0.455);
		}

	}

	// calculate pounds
	if ( (weightform.kilogram.value != null &&
	      weightform.kilogram.value.length > 0) &&
		(weightform.pound.value == null ||
	    	 weightform.pound.value.length == 0) )
	{
		if (checkNumber(weightform.kilogram,"Kilograms"))
		{
			weightform.pound.value = (weightform.kilogram.value / 0.455);
		}		
	}
}

// used for weight conversion
function clearWeightForm(weightform)
{
	weightform.kilogram.value="";
	weightform.pound.value="";
}
// -->