idea notebook; material notebook
Primarily used by comedians, writers, or performers to jot down jokes, stories, or material ideas.
Comedians always carry an idea notebook with them.
performance log; backstage notebook
A notebook kept backstage at entertainment venues to record the day's acts, preventing repeated material.
They record today's performances in the backstage notebook.
Variant using 帖, also meaning notebook; less common than 帳.
Compound of ネタ (material, idea, from reversal of 種) and 帳 (notebook).