ExIf Lens Information

I think I have managed to accomplish all that I wanted with ExIf except for one thing. I still want to store lens information in the ExIf info. Unfortunately, the only place to do that is MakerNotes, and I don't know how to work with them. It is my understanding that I would have to pick a specific set of makernotes to use for this, but I'm not even sure how to go about that. Because of the nature of my project I am not tied down to one particular set of notes, but that also means that I don't need all of the tags included in a full set. I can't make heads or tails out of how makernotes function. Do I have to somehow specify what the notes are? Are there internal references between the notes that tell photo viewers what each tag is? I don't have a clue and its starting to get to me. Is it possible to create my own maker notes? My guess on that is no, since everyone seems to be desperate to track down makernotes for every major camera ever created. I feel like I am Googling in circles at the moment trying to make things work.