This is BLFS-BOOK version r13.1 dated September 2nd, 2026. This is the svn branch of the BLFS book, currently targeting the LFS development 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.