A unique id for the weblet. The default is the same as the name property and normally you would leave it as that. In some special circumstances you may have multiple weblets, in multiple forms, visualizing the same field. In those cases you would need to set this property to give each one a unique ID.
$name The same as the name property
Any string starting with a letter ([A-Za-z]) followed by any number of letters, digits([0-9]), hyphens ("-") or underscores ("_").