Replacement remote control codes...

About that BIG mess of zillion codes television brands use with their own remotes; please refresh my memory...
Older TVs use 2 or 3 digits. Newer use 4 digits. Late models may use 5 digits for programming.
Older remotes do not accept programming of more digits than designed for.
'Universal' remotes must match the number of digits the TV code uses.
Every 'universal' remote brand has its own list of codes which are not 'universal'
To match a TV. A XXX brand 'universal' remote takes code zzz for a given TTT brand TV and such code is not useable for a brand BBB 'universal' remote.
Old 'universal' remotes do not work with newer TVs.
Newer TVs cannot use an older 'universal remote if the programming code is a different number of digits.
The 'universal' remote has to be newer than the TV and provide the correct code for the model; or won't accept programming.
All these codes work only on the brand of 'universal' remote that lists it.
Unlisted brands are a lost case. There is brands that do not work at all with 'universal' remotes.
Codes are not related to the actual digital infrared signal emitted by a remote.
Codes relate to a SET of emissions decided by manufacturer.
Remotes may have absent keys for some features/functions.
There is also RF emitting remotes, not infrared.
And that is only TVs. VCRs, DVDs, combination of devices, stereos, aux, home theatres... multiply the diarrhea by like 10.

What a nasty vomitive mess. Question is, what am I forgetting above to have it clearer? Too late to make standards...

Your post is highly confusing? - if you're simply referring to 'Universal' type remotes, then they need more digits now as there are more potential uses for them.

And why on earth would you expect compatibility between different universal remote manufacturers?, do all Ford spare parts also fit Toyota? - different manufacturers, and different copyrights.