On-the-wire refers to serialisation (writing to file or socket). It would be great to be able to specify both in-memory layout and serialised layout: the former

On-the-wire refers to serialisation (writing to file or socket). It would be great to be able to specify both in-memory layout and serialised layout: the former typically contains padding, which is a waste of space in the later. There may also be endianness differences, different datatypes, etc. That would remove the need to manually write de/serialisation routines if they should differ.