This post is dedicated to listing the various sections within a .lev file, and as time goes on, hopefully giving their function and linking to posts about them. Might have missed some, of course.

• DDCF: Length of whole file
  • EDIT: Tileset filename and layer names
  • EDI2: Same in every file; probably originally used for saving or editing or something
  • LINF: Level Information (level name, next level, music, some other stuff?)
  • HSTR: Hint Strings (text)
  • TILE: Length of tileset section, plus another long of unknown purpose
    • INFO: Tile types (translucent or not)
    • DATA: Tileset image data
    • EMSK: (bunch of longs)
    • MASK:
    • ANIM: Probably the animated tiles
    • FLIP: List of all tiles appearing flipped in the level
  • LAYR: Length of layers section, plus another long of unknown purpose
    • INFO: Layer properties (size, speeds, etc.)
    • DATA: Level layout
    • EVNT: Event map (data2 in .j2l)
  • TMAP: Whether layer 8 is textured or not
  • CMAP: Color Map (palette)