Parameters & cues

#The range criterion

A parameter and a cue both produce change: a parameter gives the change to the reader, a cue keeps it on the author's timeline. The criterion between them is the range. A change belongs to a parameter when one sentence remains true across the parameter's whole range, and to a cue otherwise.

#A parameter as a claim about its range

parameter(var: k; range: [0, 5]) asserts that the narrative holds anywhere in [0, 5], since the reader can reach any value in it. The prose therefore describes the range rather than a point.

• Holds across the range: "At degree one the fit misses the curvature; past three it memorises the data."
• Does not: "The fit passes close to every point" — true at one setting and false at most others.

Where a single value supports the sentence, that value is the author's and a cue expresses it. The criterion restricts the degrees of freedom a document exposes to those its argument covers.

#Choosing between cue and !cue.to

• A mark that arrives is wrapped: cue{ … }(in: 2).
• A value that changes carries a keyframe micronode: x-domain: [0, 5] !cue.to{[0, 10]}(at: 2).
• A mark doing both is wrapped and carries a chain.

Motion covers the anchors and durations both forms take.

#Auditing an existing document

The criterion applies to documents already written: each parameter is moved to both ends of its range and the scene reread. Prose that is then false indicates either a sentence to rewrite or a parameter that should have been a cue.