(Text taken from the ReadMe file inside the archive)
This is the !System distribution of modules to update machines prior to those running RISC OS 5. If you already use RISC OS 5 then this distribution will do nothing since the disc image and ROM already contain the same (or later) versions.
Do not use the merge dialogue in !Boot > Configuration > System Merge because part of the update must refresh files in a directory that the merge dialogue cannot reach. Instead, a simple obey file called !SysMerge is included.