Comment 9 for bug 578741

The problem is that there is no good format for that. Sad but true:
PSD: propietary, the specs where disclosed up to version 6 or something, no longer open (unless you pay).
TIFF: extensible and very powerful, but there seems to not be a standard way of saving things in it (correct me if I'm wrong).
XCF: might do but the developers don't have documentation and it has limitations. Discouraged as an exchange format even by its developers. Will be obsoleted by GEGL and XCF2 will superseded it. That might do but it's too soon to know yet.
Open raster: what's exactly the status on this? I only see somewhat old news (about a year time).