Don't get too excited, since I don't see us calculating everything out to metric.
Just be glad we are not using things like Hands. The amount of people who know and use that measurement is pretty much limited to horse people. Even the way it is written is confusing since the number after a decimal place is showing quarter hands. So a horse that is fifteen and a half hands high would be written as "15.2 hh".
@InfinityzeN : Yeah, I can imagine it is an enormous amount of work to check all those spells. That's why I wrote to the OP. I gladly do the calculations for every spell in the would-be grimoire and rewrite that part which contains the units of measurement.
I can totally relate to this story about horse people. My fater was a farmer and they used all kind of near-esoteric stuff to measure field, animal and different kind of crops. Like: "handful", "golden kroner", "stone", "fathom". Maybe that is the cause why I hate non-SI measurement bc I never really got those units. 
Don't apologise for commenting. It's fine. 
Although I'm going to have to disagree with everything you said. 
First, I'm outside of the USA. Most of us are. As a Canadian, I'm stuck with a dual system. Stuck being taught both the metric system and the imperial one because Canada uses metric but our economy's so tightly integrated with the US that I need to know it too or I'll be dysfunctional when buying consumer products (most things measured in liters and then a recipe talks about ounces and pints, some things are measured in meters, others in inches and foot... it's a pain). I'm pointing this out to illustrate that I'm not arguing for my parish because I enjoy the imperial system and don't want to deal with learning the metric system - I know the later and I don't enjoy the former either. And definitely converting everything to paces doesn't help me, it makes my conversion job longer.
Also, although the game appears to use the imperial system, it doesn't really, or at least not the full US imperial system, it's an odd ball version that feels more medievalish and includes things like:
The reality is that when you're saying it would be a great help to people outside of the US to convert everything into a pace because you can conveniently decide it's really a meter and it saves you time on converting units:
At some point, using paces and feet was an editorial decision for the game line. If it was my decision, I wouldn't use paces and leagues anywhere in the game, or if I did, I would ensure their definition is clearer. It's not my decision - I'll accept the measurements offered by the game line, whatever they are, and I'll calculate the conversions I need to make when I use it in my games if it's important to me. I'm not planning to change paces to feet, even though if I use it in my game, that's most likely what I'll do if measuring is important. I hope you won't mind if I expect you to do the same calculation from feet to paces if it feels neater to you because a pace is a meter in your group, and not ask us to impose your measuring house rule on the game line and everyone who plays it.
Putting this here rather than going to comment on a LOT of single spells.
Now that we've started into Josephine's section of the Grimoire we're getting a lot of additions of +1 Herbam requisites. I've been under a possibly mistaken assumption from my (admittedly brief, maybe an hour) research that the majority of clothing in the 13th century was leather, wool, and silks. How common really was linen or herbam fabrics outside of underthings?
Certainly more common than silk or leathers. Linen was harder to dye than wool, and more resistant to soiling - but both were commonly used for all kinds of clothing. Regional preferences depended on availability. Early manufacture preferred wool in Italy, but linen in Northern Germany, Flanders and Brabant.
The Lower Rhine area was the region of Europe with the most linen production capacity during the middle ages. And any location which traded with Egypt had access to a range of herbam fabrics.
Very valid errors in my spells around sizes and volumes - Imperial units do not make sense to me at all. I apologise.
No need to apologize. I was just a little grumpy after spending most of a day having "Oh.. another one I have to recalculate" moments and so I should apologize if I came across as harsher than I should have. Consider it payback for my group and I 'borrowing' ideas from your blog for years. Never realized the math was off since we would take the idea and design our own spell/effect from it.
Your tapestry that contains many scenes idea became an NPC Magus artist in our saga that our Covenant bought many paintings from and is one of the Vendors in the Tribunal Fair Collection thread.
My research was different, but my research was short, and google-based. I'm not an expert - I also had only sagas based in regions with lots of sheep and goats. I'm happy with adding herbam requisites or restricting targets on those spells, make sense.
New question for general agreement: I'd prefer to avoid spell bases not based on 5's, since that's how most magnitudes are calculated in (I think) every official product. Are we sticking to that? The aquam damage calcs are bringing it up and I'd like to just make a decision.
I used to believe that raccoon, where spells were 1,2,3,4,5 and then multiple of 5s, but someone pointed out to me I was incorrect. "Most spells are assigned a level, which is usually a multiple of five. It need not be, however, and magi may well invent spells of intermediate levels. Spontaneous spells often have other levels, as well. Some spells are General spells (abbreviated to Gen), which means that they may be learned at any level of difficulty — the higher the level, the more powerful the spell." (AM5 115)
As long as we're dealing with guidelines using General, yeah, you can decide to learn a level 23 spell. It feels weird, but it's allowed in the book.
I feel like we need to make sure that we point this rule out in the final PDF.
There are however cases where the level calculations can get ... odd.
Take for example a classic General spell with a General guideline: Demon's Eternal Oblivion
If I want to invent a level 18 DEO then that is no problem: Base level of 8, +2 magnitudes for R:Voice, final spell level of 18.
But inventing a level 11 DEO is more problematic. Base level of ???, +2 magnitudes for R:Voice and a final spell level of 11. Problem is, there is no base level such that adding two magnitudes will give a final spell level of 11.
Demon's Eternal Oblivion includes the +2 voice. A level 18 DEO does 18 might damage, and a level 11 DEO does 11 damage.
Uh-huh. What I am saying is that the level calculation for a level 11 DEO gets whacky, since the level is base + 2 magnitude for Voice.
Note that the guideline it uses says it does Base level + 2 magnitudes of damage.
Right, I think I get your point. Should we allow DEO 3-5, DEO 10, DEO 15+, but not allow DEO 1-2 (with base of -1 and 0), DEO 6-9, and DEO 11-14, because of the mathematical impossibility of applying 2 magnitudes to generate those numbers using a non-fractional number equal or superior to 1? It does look mathematically impossible, if applying normal spell notations.
The game line seems to alternate between normal spell notations (Base 3, +2 voice) and not calculating it at all (Base effect, +2 voice). I'm leaning towards considering magnitudes applied in RDT towards free magnitudes that are included in the guideline to not matter, and to apply the (Base effect, +2 voice) description to avoid describing a base of -1, 0, or base 3.2, 3.4, 3.6, 3.8, 4.2, 4.4, 4.6, 4.8 which would justify the oddball levels we're talking about. It doesn't look neat to me to say DEO 16 to 19 are allowable, but DEO 14 isn't. I can't say there's an actual RAW answer. Does the community feel strongly about this way one way or another?
As a side note, we have at least one General spell with an abnormal level, in TTA 126, where we have a lab text for a ReVi 32 Tie The Threads That Bind spell, so at least that part is confirmed to have been used by the game line somewhere.
Commenting here for ease:
I have been finding lots of spells which attempt to work in the same manner as Trackless Step. However that is a legacy spell which was errata'ed to note "This spell draws on pre-Hermetic traditions, and does not perfectly fit the categories of Hermetic magic" and thus not valid for designing other spells to work like.
The Hermetic way to get a Trackless Step type effect would be to target the person rather than the medium they were walking over. Some ReCo Base and/or a Ward. For example moving over something without leaving tracks is ReCo Base 4 (Surface that cannot support) which would mean that magic supports their weight. The Duration of Trackless Step could be done however. It is a non-standard Concentration and cost one Magnitude more.
"Hermetic Trackless Step" is ReCo 10, P/Spec/I, Base 4, +2 Special (equivalent to Sun).
To avoid further cluttering up the document.
A burrow shelter is an emergency or traveling shelter for a single sleep rather than a long term one. Build a small domed mound of a material (snow, leaves, hay, etc) with just enough space worked into it for one person to fit snugly (two if they spoon). Pull in material to mostly block the entrance after you are inside (leaving just a small "fresh air" passage). It provides insulation and protection from wind/weather. When you exit it is normally destroyed.
There are all sorts of names for them based on the material they are made of and location of the person asked. However they are the simplest shelter you could build with minimal effort when you only plan to use it for one night. Variations have been around for millennia.
Question about ice and natural shape - reading the later ice-walls, we tend to agree that a wall of ice isn't natural... Then I thought, except if the ice is forming down the side of a wall or cliff, in which case it's normal. But we also allow an icicle as a club, even when there isn't an overhang for it to hang from. What do we consider a natural shape for ice at this point?
@raccoonmask In those cases I tend to use not just my common sense (AKA what is frequent in nature? ) but also the Platonist paradigm. Based on that I think creating solid materials in simple shapes is an easy task for Hermetic Magic. Those shapes are circle, triangle, square ans spatial forms like sphere, cube, tetrahedron, rectangle.
An ice wall is just a big rectangle. Even a ring shaped wall is quite simple I think.
But if you do not have proper size and want to trap
somebody indise the ring of wall you have to roll for Aim.
All in all I would not add any magnitude to the Wall of Ice spell for being in unnatural shape.
Kind of similar opinion, but I want us to have an agreed decision on how we're hadnling it for the Grimoire.
I also think we should note at the beginning of the final that this was fan-submitted and fan-reviewed, so everything should be taken with the understanding that we tried to be as true to the Core RAW as we could, but each Saga should use their own interpretations as to what they accept.
I have to say that coming into this project, I didn't realize how enlightening it would be.
Sure, myself, am not doing much of the critique, but seeing the discussions both here, and in the comments on the document, I love it, and I feel like they are very eye opening.
And I want to thank everyone who is participating with the critiques.