In another thread, a question was posed about a CrTe ((Ritual) spell to create a lump of silver...
And that raises the question in the subject line - how much flexibility does a Formulaic Spell have?
The guidelines for most any Te/Fo combo typically state something along the lines of: "Apply the Technique to X general category of Form" - but does that mean that a single spell can cover any of that example, or only one very specific example?
The question above is a good example. The CrTe Guidelines state "Base 15: Create precious metal" - so does the spell description read...
"Create a lump of silver"?...or...
"Create a lump of a precious metal"?
More, does/can a spell using Base 15 encompass Base 10 and lower as well? Does a ReTe spell that affects metal also affect gems, stone, glass, sand, mud and clay?
I can find little in the rules to clarify how variable a single spell should be, and different canon spells (especially some found in supplements) seem to apply widely different guidelines. (Especially in the Imagonem and Mentem categories, sometimes a spell is very specific and sometimes very flexible.)
I doubt if there is a canon answer, so this thread may well be an exercise of kicking the question around and giving "ims" examples. For instance...
Ims, I allow some but not a lot of flexibility. In the above example, the spell would have to specify the type of metal, but with a Finesse roll I'd say different types of silver might be produced - pure, sterling, whatever. For CrIm, the effect is limited to one "type" of thing - a horse, a wolf, a tree, but details within that limitation are up to the mage (and a Finesse roll). However, I also allow +1 magnitude (or more) to be added to create some flexibility - any precious metal or any animal or any bush/tree/etc - something like that.
So...
CrTe 15
A Disposable Mortar*
Create a ceramic bowl that lasts Moon Duration.
(Base 3, +1 Touch, +3 Moon)
...or...
CrTe 25
Disposable Lab Equipment*
Create a glass, stone or ceramic flask or bowl that lasts Moon Duration.
(Base 3, +1 Touch, +3 Moon, +1 elaborate shape, +1 flexible)
(* Note that, by the Covenant rules (p 122), if either of these spells were used to gain a lab bonus (for instance to save money on Upkeep), it would also add to Lab Warping.)
I've considered a loose houserule that if a spell is overly specific it receives a -1 magnitude adjustment, but it would have to actually be a limitation on the spell itself - creating only 1 type of wolf would not be a disadvantage, but creating only 1 specific illusion might well be. (The IG rationale for this involves Platonic Forms, and how a single specific PF is easier to incorporate into a spell design - or something.)
This is all extremely subjective, but short of adding a LOT more to the guidelines (specific categories and sub-categories for every class of example of that Form), I'm not sure how else it should be addressed.