Locally installed software must be placed within /usr/local rather than /usr unless it is being installed to replace or upgrade software in /usr.[footnote 23]
Local game binaries
Local C header files
Local online manuals
Local system binaries
Local architecture-independent hierarchy
Local source code
No other directories, except those listed below, may be in /usr/local after first installing a FHS-compliant system.
 Software placed in / or /usr may be overwritten by system upgrades (though we recommend that distributions do not overwrite data in /etc under these circumstances). For this reason, local software must not be placed outside of /usr/local without good reason.