A warning beforehand. You can find this information at byte 29 in the binary file. This document describes the matlibs .mli files generated by 3D-Studio 4 and I think it covers nearly all of its aspects. If not you can contact me or Martin van Velsen or Jim Pitts to add or correct. First parts of .3DS files include material definitions with the same format than .mli, if you want to understand this part of .3DS files you can refer to this document.
Pointers point to the next chunk of the same level.
The pointer of the last chunk of a subset points to the next chunk level above. Chunk ID is 2 bytes, pointer is 4 bytes. If I am not clear you can read the .3ds file format doc. The Main chunk is the whole .MLI file. Its ID is 3DAA and the pointer is in fact the length of the file.