The udev-lfs set of files is a customization of systemd.
In 2012, udev was merged with systemd and a build methodology
incompatible with LFS.  These files extract the udev
code from systemd for LFS.
These files are distributed in the form of a tar file available
from the LFS file mirrors.  The tarball is created with:
mkdir /tmp/udev-lfs-$VERSION
cp -av * /tmp/udev-lfs-$VERSION
tar -jcf /tmp/udev-lfs-$VERSION.tar.bz2 -C /tmp udev-lfs-$VERSION
Makefile.lfs         - The main LFS Makefile.  Builds and installs
                       udev from systemd sources.
makefile-incl.keymap - BLFS makefile for keymap and supporting files
makefile-incl.gudev  - BLFS makefile for libgudev
makefile-incl.gir    - BLFS makefile for GObject files
contrib              - Useful rules from debian
contrib/debian
contrib/debian/83-cdrom-symlinks.rules
contrib/debian/write_cd_aliases
contrib/debian/81-cdrom.rules
55-lfs.rules         - LFS custom rules
write_net_rules      - Scripts for LFS rules
write_cd_rules
rule_generator.functions
55-lfs.txt           - Documentation for LFS installed rules
cfg.h                - Basic info needed for udev compilation
ChangeLog            - Log of changes to 55-lfs-rules
init-net-rules.sh    - A script for establishing persistent network
                       rules before the first LFS boot