In the documentation for custom instruments I see a reference to the "advanced modeling guide"?
Any chance we could make that available to the dozens (yes there are dozens!) of us writing custom instruments?
Please file a radar (mainly because if you file the radar you can track it easier) and we'll take a look at getting an update to the documentation in as soon as possible. Unfortunately there is no public, comprehensive document on writing advanced modelers that I can point you to at this time.
Radar 47225585 file as requested