In the RouterOS v2.8 docs under the ‘Customizing Hotspot Servlet’ section, one finds a variables listing. i’ve found most of these variables easy to work with but can’t for the life of me get ‘session-id’ or ‘var’ to take on any values… the docs say, for eg, “session-id : value of ‘session-id’ parameter in the last request”… what is the “last request”, and is this session-id at all related to the radius parameter Acct-Session-Id 
If i remember correctly, these variables are derived from the request itself, i.e., if you request tha page containing the variables by specifying the values of these variables in that request, the variable names will get substituted. Though I may be wrong… long time has past since I’ve known this 