Documentation for Velocity Context

Is there some documentation about what is exposed in a velocity portal page?

eg.

		#if ($filterClients)

		<div id="advanced-search" style="display: none;">

			<span class="field-label"><label for="form_access">$form.fields.clientSelect.label</label>

			$form.fields.clientSelect

			</span>

		</div>

		#end

		$form.endTag()

	</div>

</div>

<div class="row"><hr></div>



## See template in: /resources/includes/account/tile.htm

<div id="tableHolder" class="row">

	$tileList

</div>

Is $form the same form from the core api?
What methods does it support?
What is $tileList?
What other variables are exposed?
Can I access the user's session information?

Matt