As a wizard with Great (+4) Conviction and Discipline, I can have the following rote spell:
Type: Earth evocation, defensive block Power: 4 shifts Duration: One exchange
Can I choose each time I cast the spell whether the effect works as block strength, Armor, or a zone border (YS, p. 252)? A rote spell "always manifests in exactly the same way each time" (YS, p.257), but I'm not entirely sure what counts as "the parameters of the spell".
Your Rote must either be an earthen Armor or attempt to fully Block a type of action. You can always roll for the other, or establish a second Rote for the other effect.
Parameter isn't a defined game term, so defaulting to general English,
a numerical or other measurable factor forming one of a set that defines a system or sets the conditions of its operation
We can see that measuring your Block or Armor will change and as you noted (emphasis added),
Any change in the parameters of the spell disqualifies it from being a rote.
(Your Story, p. 257)
Further, it seems implied that each of the paragraphs that begin with red text under Block (Your Story, p. 252) would be the precise things considered parameters.
It is explained that if your spell (even a Rote Block) had not been used for its purpose in the previous exchange, and is still maintained, you can alter the spell to perform a new function. In such a case, you can reshape the Block/Armor to be the other form so long as you can narrate how you are able to accomplish this.
