Clipboard

A clipboard was a simple stationary holder, dating back to the 20th century, consisting of a thin board with a clip at the top for holding paper, sometimes containing a cover.

Clipboards were used through the mid-23rd century where they were for delivering reports on board Federation starships. These clipboards had a lid customized with the Earth-Federation logo and starship's name. These clipboards were used until at least 2265. 

Background
In the case of Dr. Elizabeth Dehner from "Where No Man Has Gone Before", this form of "space clipboard" was given to actress Sally Kellerman because she felt embarrassed that her tight Starfleet uniform costume was particularly close-fitting at her crotch area, a problem that director James Goldstone intended to cover up (and successfully did so) by instructing the propman to provide her with such a prop. (Inside Star Trek: The Real Story, p. 84)