You normally don’t create a representation with a login appearance. The login appearance is used ‘automatically’ if a page is specified as a secure page. By default, all pages behind /admin are considered secure.

To add security to the theatre, please read

Login appearance

The login page will appear when a user requests a secure page and is not signed in. So the login page is normally only displayed once. After the user has entered his credentials, the original (secure) page will be presented, and a user can navigate between secure (and non-secure) pages. The @USER@ will contain the username of the user and can be used to filter content. For example:

stage:SecurePage a elmo:Representation;
	elmo:url-pattern "/admin/query/secure-example";
	elmo:query '''
		construct {
			?person ?pred ?obj
		where {
			?person foaf:accountName "@USER@";
			?person ?pred ?obj

This example returns triples for a person that has the same accountname as the signed-in user.