// Grab the document size, 0x1c -> 0x1f
docSize = LittleEndian.getUInt(_docstream, 0x1c);
// ??? 0x20 -> 0x23
// Create the Chunk+Pointer Factories for the document version
ptrFactory = new PointerFactory(version);
chunkFactory = new ChunkFactory(version);
// Grab the pointer to the trailer
trailerPointer = ptrFactory.createPointer(_docstream, 0x24);