function enableField(target_field_id, source_field_id, source_value)
{
	var target = document.getElementById(target_field_id);
	var source = document.getElementById(source_field_id);

	if(source.value == source_value)
	{
		target.disabled = false;
		setDisabled(target, false);
	}
	else
	{
		target.disabled = true;
		target.value = "";
		setDisabled(target, true);
	}

}

function setDisabled(target, isDisabled)
{
	var classes, i, class_list="";

	if (target.className.indexOf(" ")!=-1)
	{
		classes = target.className.split(" ");
		for(i = 0; i < classes.length; i++)
		{
			if("disabled" != classes[i])
			{
				class_list += classes[i] + " ";
			}
		}
	}
	else
	{
		if(target.className != 'disabled')
		{
			class_list = target.className + " ";
		}
	}

	if(isDisabled == true)
	{
		class_list += "disabled"
	}
	target.className = class_list;

}

function limitText(limitField, limitNum) {
	if (limitField.value.length > limitNum) {
		limitField.value = limitField.value.substring(0, limitNum);
	}
}