The Spire.Doc API documentation does not give much explanation about many object properties.
One example is the IDocumentObject.IsComposite Property.
This property is implemented by many types of class, and the API documentation for each of them refers us back to the definition of IDocumentObject.IsComposite, which tells us, basically, that it is a boolean value.
I cannot find any more in-depth documentation on the various classes, properties and methods in the Spire.Doc API. It looks like it is quite a rich and powerful API, things are all just a little bit different than the Office Word API, so a few sentences of explanation on each page of the API documentation would be very helpful.