Inductive compressionMethod : Set :=
  | CompressionUncompressed
  | CompressionBC1
  | CompressionBC2
  | CompressionBC3
  | CompressionBC4
  | CompressionBC5
  | CompressionBC6
  | CompressionBC7
  | CompressionETC1
  | CompressionETC2
  | CompressionEAC
  | CompressionASTC : nat → nat → compressionMethod
  | CompressionCustom :
    ∀ (d : descriptor)
      (blockSizeX : nat)
      (blockSizeY : nat)
      (identifier : nat)
      (align : nat), 0 < align → compressionMethod.
