This format is a raw binary image of the memory data in a file. There are no headers, no comments, no coding. The file is probably not editable in a common text editor.
In the big-endian mode the memory is considered as a sequence of bytes regardless of the size of its words, with left to right the high bytes and then the low bytes. Illustrations can be found in v3.0 hex bytes addressed big-endian

Binary data little-endian

This format is identical to the previous one with the same characteristics.
In the little-endian mode, the memory is considered as a sequence of bytes with from right to left the least significant bits and then the most significant bits. Illustrations can be found in v3.0 hex bytes addressed little-endian

Next: Pop-up menus and files.