This is BLFS-BOOK version 11.3 dated March 1st, 2023. This is the 11.3-systemd branch of the BLFS book, currently targeting the LFS 11.3-systemd book. For development versions, if this version is older than a month, it's likely that your mirror hasn't been synchronized recently and a newer version is probably available for download or viewing. Check one of the mirror sites at https://www.linuxfromscratch.org/mirrors.html for an updated version.