Entasis

A term indicating both the specific part of a spell used to handle its energy outlay and management, and the energy "numbers" themselves -- data on energy input, output, and the degree of inherent balance of the spell. The English version of the word is derived from an old Greek compound meaning "to stretch something out tight", and invokes the additional (and for a wizard, inevitable) concern about a spell's energy being used to maximum possible effect for the least possible energy outlay.

In SYWTBAW, Tom Swale asks Fred for the entasis numbers on his "warp" -- (probably meaning his internal temporospatial claudication) -- with an eye to curing Fred's hiccups. (SYWTBAW et al.)