HexEdit

The DATA and RSRC displays are showing you the raw data of the data and resource forks of the file, respectively.

The information they display will only make as much sense as the data in those forks, in this case it will be pretty much meaningless.

So, when you are looking at the DATA view, you are not actually looking at commands, you are viewing information in the data resource of whichever file you have open. These may look like commands, but they are not. (Thus the lack of documentation, because what you see will vary based on the file you choose to open, it's different every time.)

Editing a program in this fashion is an extremely advanced topic, and requires a very good understanding of PowerPC assembly language and machine code.