What each setting does
One page per group of settings, plus an honest list of what the product will not do. Written against the code, not from memory.
Direction: one-way or two-way
Push copies one way and never touches the source. Mirror goes both ways. How to tell which one you need, and what changing it later deletes.
Appearance: how copied events look
Every setting that decides what a copy looks like when it lands: title, availability, privacy, colour, guests and reminders.
Filters: which events get copied
Which events enter a sync at all: the RSVP filter, working hours, Google's special event types and exclude rules — plus what tightening one deletes.
Sync details: name, history, and how far ahead
The sync-wide settings: a sync's name, how much history it copies on its first run, and how far ahead it reaches.
Calendar exceptions: different settings per calendar
Set a shared default for a sync, then override it for one destination calendar. What you can vary, what you can't, and which way round it works.
Plans and limits
The five numbers that limit a setup, what each one means, and which one actually stops people.
What SYNCDATE can't do
The limits no plan removes: syncs don't chain, special event types are Google-only, feeds are read-only, and colour is approximate between providers.
Looking for the answer to a specific problem rather than a description of a setting? Guides covers that. Ready-made setups live in recipes, and support will look at your actual setup.