</pre>
* If any of the functions is called outside the servlet context, <code>[[XQuery Errors#BaseX Errors|basex:http]]</code> is raised.
* If the requested a specified session id is not found, <code>[[#Errors|not-found]]</code> is raised.
* As sessions are side-effecting operations, all functions are flagged as ''non-deterministic''. This means that the functions will not be reordered by the compiler.