Learning Spells from Text

Can I just not find the relevant place where this is described in the rules?

As I'm still in the transition from 4th to 5th, and have yet to try and play 5th, we hit a bit of a snag yesterday during some character creation. We remember the 4th ed rules for learning a formulaic spell from a text in the library.

But has the 5th ed rules changed libraries from having spells on text to having Lab texts in said spells. And when a magus is "learning from text", he is really inventing his own version of it, but quite easily as he is using a set of instructions from another magus.
This would also explain why the "Covenants" book list Build Points for various books and lab textx in the library, but not spell levels.
This sounds like a very good idea, as it simplifies Lab Texts - no longer will you have to record the Magic Theory score of the magus at the time - plus they give a huge benefit.
But what are the rules for writing up Lab Texts? Before this, you automatically produced them as you invented stuff. Now, they're worth so much more, and I'd think they would take actual time and effort to write.

This explains something about no "casting spells from text" option - which btw I say good riddance of! In previous campaigns, magi hauled along a handfull of important spells (flying, tracking spells, teleport, haunt of the living ghost etc.), to cast. Spells they could not normally learn, or just didn't bother to spend the time. Often, they had enough time to recover from any extra Fatigue loss to make up for low casting scores, so it really didn't matter. It almost newer went wrong, even though it cost extra botch dice. I tried to foil it, by keeping them n their toes at all times, and having weather wreck havoc with the vulnerable scrolls. But they just made do with what little time they had in peace to do the castings, and had a super-scribe make a load of copies. Never mind, this is going a bit off topic.

Indeed. You might be interested in reading the design notes on the laboratory chapter.

No, they're still free. And still need translating from the writer's shorthand too, if I remember correctly (serf's parma).

An interesting problem...
The Covenants book does allow one to cast from text, offering "casting tablets" as a means to do so. If you don't like them, you can choose not to include them in your saga.

I'm not sure what works best personally. I'm attracted to the idea of not allowing them too - magic is, after all, a very personal thing.

Check page 102 of the core rulebook. The section on "Writing Laboratory Texts" tells you what you need to know.

The magus does create a lab text for each activity but these notes are filled with his own "abbreviations and shortcuts". But he can spend a season or more scribing them into a usable form.

I seem to remember it being much the same under fourth, but the details may have changed.

Lab texts in shorthand:
Yes, this makes perfect sense, they're only "free" (re: time) for your own purposes. But for others to use, you must still write up a Lab text from shorthand to full text. And when inventing a nice spell, you'd do this, to sell the lab text to other magi and covenants, to add to their "spell-library"

Casting tablets:
Yes I saw these too, and I'm thinking about whether to adapt them. First off, I need to re-read the rules. Since "spells on text" no longer exist, but magi use Lab texts to learn this way (as opposed to getting the spells taught or invented from scratch). So there must be some mechanic to write the spell from the lab text stage and up to actually being able to cast it. Second, I'll make sure the rules make then less portable and convenient than scrolls. perhaps I'll demand the "vis capacity" of device is used to define how many magnitudes can be put on such a tablet. So I'll do some math, so the tablets may need to be made from stone or metals. Third, IIRC they say, that casting tablets allow such inflexible magic, that things must be done in that particular way, and have this be inconvenient.