CMU Window Manager bitmap

CMU Window Manager bitmap (possibly also known as ITC bitmap) is an uncompressed bi-level raster image file format. It was apparently used by old versions of the Andrew Toolkit.

Format
There are evidently several varieties of the format, which differ in the size of the header, and the byte order of the header fields.

According to Netpbm, files have a 14-byte header containing a signature, width, height, and depth (which is always 1). The signature begins with the  byte, and the header fields use big-endian byte order.

The file command thinks that the header is at least 16 bytes (depth being 4 bytes instead of 2), the byte order is little-endian, and the signature still begins with.

The ATK 6.3 source code implies that the header can be 14 or 16 bytes, and that the byte order is indicated by the signature.

(Yes, we know that all of these things cannot be true at the same time.)

Identifiers
The standard filename extension is unknown, but .cmu is sometimes used.

Identification
Files begin with signature bytes, or.

Software

 * Konvertor
 * Netpbm: cmuwmtopbm, pbmtocmuwm
 * XnView
 * ftp://ftp.andrew.cmu.edu/pub/AUIS/auis-6.3/atk/raster/lib/ → oldrf.c