Similar to the ctrl/ftpalias.cfg file, the new ctrl/web_alias.ini file (optional) can be used to map a portion (the first portion, only) of a web request path to a different physical or virtual path. For example, I'm using it to map:
/Synchronet/ = /files/main/sbbs/
for filebase access to my main->sbbs directory of Vertrauen's filebase using a /Synchronet/* web request (i.e. for slightly prettier or shorter custom URLs, if desired).