The compressed random access file format is used by Simics's image module to handle sparse block data. The craff command-line utility can be used to create and manipulate craff files.
The general craff usage is:
craff [options] files ...
The default operation is to merge the input files, each of which can be either in craff format or raw files (e.g., disk or memory dumps) and to output the merged result to an output file. The order of the input files is important: data from later input files override earlier files. Since craff files can have holes (gaps) in them, data from earlier files can propagate to the result.