FHS 3.0 was released June 3, 2015 on /var/lib
APT HOWTO (Obsolete Documentation) How to deal with errors
/srv/ - not part of FHS, site-specific data, served by the system /usr/ - secondary hierarchy for shareable, read-only data, formerly from UNIX source repository, now from UNIX system resources, -- files that are not required to boot or rescue the system. the same debian wiki page](https://wiki.debian.org/FilesystemHierarchyStandard)
Various notes on /usr unification / February 28, 2012 "/usr unification" (or simply "usrmove") is the idea of moving the contents of /bin, /lib, and related root-level directories into their equivalents under /usr.