The Segment Spec has three components.
First, it outlines the semantic definition of the customer data we capture across all of our libraries and APIs. There are six API calls in the Spec. They each represent a distinct type of semantic information about a customer. Every call shares the same common fields.
Second, it details the event data we capture across some of our cloud sources and destinations.
Third, it shares the events we recommend you track for a particular industry based on our experience working with thousands of customers. When you respect these specs, we can map these events to particular features within end destinations like Google Analytics and Facebook Ads.
If you have any questions, or see anywhere we can improve our documentation, please let us know!