Jnlib layout files are used to define positions of elements on the screen. These files are BNCL, BNBL, and BNLL. They share a common header and coordinate structure. The header of these files is structured as:

Jnlib layout files use a common structure for storing coordinates. This allows for storing a coordinate relative to one of 9 points on the layout element. These take the following structure:

AA OO XXXXXXXXXXXX
|  |  |
|  |  +----------- The coordinate as a signed 12-bit integer.
|  +-------------- The origin. Can be 0 (left/top), 1 (center), or 2 (right/bottom).
+----------------- Text alignment. Can be 0 (left), 1 (center), or 2 (right).

The text alignment field is only used for rendering text elements, and is ignored for other kinds of file.

The origin position sets the position of the layout element with respect to one of 9 points on the element. These points are illustrated below: