The HTML Controls are found inside of HTML Forms. There are two supported names for the HTML Controls, the name and id attributes. When a form is submitted for processing, the successfull controls will have their control name and current value submitted. The control name is given by the name attribute. The id attribute is a unique identifier within an HTML and XHTML document.
Both names are determined when the page is rendered. Typically the name attribute is the databinding expression. The actual value is both dependent on the tag through the naming chain and scoping through the URL rewriter service. The tagId attribute is used to set the id. This value is always passed through the URL Rewriter service to provide scoping.