Not all airframe modifications airframes are officially approved or noted in the logbooks. Shocking as it may sound, many aircraft owners are tinkerers, shade-tree mechanics or aircraft builders. Some have even been known to make unapproved changes and mods without disclosing them to their own mechanics or the FAA.
When I purchased my 180, there was a lovely machined iPad bracket mounted to an overhead hard point where the windshield and airframe attach (an attachment point appropriate for a visor.) The eight-inch aluminum bracket was obviously custom-machined and not off the shelf. I liked it well enough until the day I realized its extremely sharp corners were a guaranteed cranium opener. I removed it. Since there was no paperwork documenting its installation, no additional paperwork was necessary.
