 DivX Plus HD devices are also tested for compliance against the DivX HD 1080p profile for MPEG4/AVI certification in order to maintain backwards compatibility  
DivX has introduced additional features beyond the Matroska specification that are implemented during the video file creation process and exposed during playback in DivX Plus software and on consumer electronics devices certified for DivX Plus HD.Below are the standard and extended MKV features that are specific to the DivX Plus HD profile.Currently, font files can be easily attached to .mkv files using a Matroska mux, but certain problems may arise when attempting to utilize a font during playback.