Definition
A cue is the elementary unit of electric firing: one physical output of a module, identified by the module number and output number (for instance 3-12), to which one or more igniters that will fire together are connected. By extension the word also means the firing-plan event that triggers that output at a given instant. A cake, a chain or an entire fan takes only one cue; a single-shot battery takes one per tube. Cue numbering follows chronological order in simple shows, or the geography of the lines in complex ones. A municipal show has 30 to 100 cues, a competition pyromusical several thousand. Every cue is continuity-tested before arming and ticked off after firing.
In practice, for the display company
The cue is the column that ties everything together: product, rack, module, instant. PyroDesk assigns cues automatically in the chosen order, renumbers them when a sequence is moved, and prints them on tube labels and the wiring sheet; PyroSimulator can display the cue number on every launch to spot a mistake.