The mechanical dobby is a program bar with pegs system. The numbered holes in the program bars correspond with harnesses of the loom. If you want a harness to be raised, you place a peg in the corresponding hole of the program bar. Your series of program bars can be as long as you like.
If the number of program bars becomes very large, you may want to consider an electronic dobby. The electronic dobby will give you almost unlimited harness combinations using a computer and software from Fiberworks PCW, Patternland, Weavemaker, Weave It, WeavePoint or Pro Weave, which all work with the Louët electronic interface.