CALS File Format Version number:
CALS was developed by the US Department Of Commerce with several US government agencies and private organizations such as the Association for Information and Image Management (AIIM). It was designed to standardize information interchange between branches of the military.
CALS files are used for document imaging and only store black-and-white, 1-bit image data. CALS Type I files only store a single image per file and the data is always compressed using the CCITT Group 4 encoding algorithm. CALS Type II files may store multiple images per file, the image data may be tiled, and tiles stored as raw data or as data compressed using CCITT Group 4 encoding.