I want to work in the mng http://www.libpng.org/pub/mng/#history format, and don't recall gimp supporting it, ie -- it's not a save option.
You can use ImageMagick in conjunction with the GIMP to do this. IM will read in .xcf files (as well as many others) and will happily then output .mng files for you.
LDR -- --------------------------------------------------------------------------- Leonard Rosenthol <mailto:leonardr@xxxxxxxxxxxxx> <http://www.lazerware.com>