This set of documentation, and the accompanying library routines, are known to work with IDL save files produced by IDL version 4.0, and versions 5.0-5.5. They work with save files smaller than 2 gigabytes, that are uncompressed and do not contain objects. Compressed save files will not be accessible at all, and cannot be generated by the library. It will be possible to access and scan save files containing objects, but not possible to restore objects.