This document doesn't really without the basis of the other one.
This document describes the requirements placed by systemd
on the time when various parts of the file system hierarchy
must be available and mounted during boot.
+This document should be read in conjunction with
+[Linux File System Hierarchy](https://uapi-group.org/specifications/specs/linux_file_system_hierarchy/),
+which describes the role of the mount points discussed here.
If the file system backing a mount point is located on external or remote media
that require special drivers, infrastructure or networking to be set up,