hrjetI had added XMP support to FLIF last year: FLIF-hub/FLIF#375
hrjetTheGreatNi: Which version are you using?
hrjetAlso, check the version of libpng being used. IIRC, versions below 1.6 don't have the requisite support.
TheGreatNiI'm testing it out by adding xmp data via xnview, then converting to and from flif