Most A:M users will never need to do something like this, but it is possible to investigate and make useful changes to an A:M file with a text editor.
You'll need your close-up glasses for most of this.
AMTextEditing.mov
Things I have done with text editing
-fixing the "dragged bone in a chor" problem (shown in this video)
-changing the name of an item throughout a PRJ
-changing a bone to a null
-finding and fixing name spelling capitalization mistakes. ("Left" instead