Some things to do with &EXT()
IncantationresultExplanation
request.filename&EXT('request.filename') full internal path of the current resource
request.uri&EXT('request.uri') Uri of the currently viewed resource
request.state&EXT('request.state') state of the resource, eith construct or publish
user.name&EXT('user.name') username of user
user.domain&EXT('user.domain') Domain the user is in
user.course.sec&EXT('user.course.sec') Users's Course Section
environment.firstname&EXT('environment.firstname') User's firstname
environment.middlename&EXT('environment.middlename') User's middle name
environment.lastname&EXT('environment.lastname') User's lastname
environment.generation&EXT('environment.generation') Jr., Sr., III, etc.
environment.screenname&EXT('environment.screenname') User screen name (name that appears in FDBK postings)
environment.nickname&EXT('environment.nickname') User nick name. (Name the user prefers to be called in person
environment.id&EXT('environment.id') user id number
request.browser.version&EXT('request.browser.version') Version of the users Browser
request.browser.type&EXT('request.browser.type') What type of browser is the user using
course.description&EXT('course.decription') Decriptive name for a course
course.num&EXT('course.num') Internal Course Identifier
course.url&EXT('course.url') Current course toplevel map.
query.* query.* allows access to the passed in form parameters
query.grade_target&EXT('query.grade_target') Ignore this. It isn't generally useful.
Other things:
IncantationresultExplanation
$external::target $external::target Whether we are printing (tex) or viewing on screen (web)
$external::part $external::part current Part id
$external::gradestatus $external::gradestatus The solved status of the current part.
$external::datestatus \verb+$external::datestatus+ The current status of the problem (CLOSE, CAN_ANSWER, etc.)
$external::randomseed $external::randomseed The randomseed currently in use.