See the title — It’s LC’s World, and we just play in it.
While mostly tongue in cheek, they are open to input from the public (and with a bit of prodding and nudging, you too can ever participate in the process!), the fact remains that it’s the Library of Congress’ subject headings, and the Library of Congress’ manual.
The headings are intended to be used by their catalogers, and the manual is there to help guide those catalogers in the headings use.
What this means in practice is that there are a lot of times in reading the memos that you’ll come across specific instructions on reporting or changing a heading which only makes sense if you work at the library of congress.
An example of this can be found in Memo H 165 which includes instructions on when to change headings in bibliographic records. None of these instructions apply to you at your institution with your ILS. They’re specifically for LC catalogers using the LC ILS.
Sure, you may want to glance at the memo, and perhaps incorporate some equivalent instructions in your local policy, but some of the instructions really are so specific as not apply more widely, unless you institution happens to use the same “Database Maintenance Request Form” (it doesn’t.)
Anyway — just a good reminder to start us off. There’s a lot to be learned from the memos, and deeper dives into it will make all our subject cataloging better and more consistent. But important to keep in mind: It’s LC’s vocab, and LC’s manual. Read it with that grain of salt, because while we can agitate for change, it serves a greater function than what we want.