[Copyright status: this file is in the public domain.]

When using PutImage and/or GetImage requests (see lx_PutImage and
lx_GetImage in core.txt), there is a need for image data - for
PutImage, the application produces it and the server consumes it; for
GetImage, the other way around.

There are two basic formats, XY format and Z format.

I need to write documentation on this.