Object files contain the graphic data that is displayed in the 3D window for each object. ie: signs, tents, towns, etc... The file is named simply xxx.OBJ where xxx is a number from 000 to 099 or xxx.0BJ for numbers 100 to 199. Note that the extension for objects 100-199 has a zero in it, not an 'O' (oh).
The object files are standard sprite files with a variable number of frames. Some objects contain frames in a sequence to generate an animation. An OBJ can has as few as one sprite frame (barrels, pedestals, trees) or as many as 24 for objects that are animated (mirror, tent) or have different states (chests). Some OBJ files will contain two separate objects that have a slight variation (pedestals). The CLOUDS.DAT and DARK.DAT files contain the data which indicate what frames are used when viewing the object from the front, back, left side, and right side, whether they're displayed normal or horizontally flipped, and the frames which make up an animation.
The X and Y position, and the direction frame are calculated from the players position and direction and the data loaded from the MAZExxxx.MOB file, and plugged into the appropriate positions in the Drawstruct list.
These images have been cropped in order to fit them on the screen. Images in gray scale are extrapolated from the animation information and are not actually stored in the OBJ file.