Hi,
SOLIDWORKS API object model contains hundreds of interfaces and thousands of methods and properties. When starting developing applications or macros for SOLIDWORKS it might be confusions to understand all the relationships to find the correct route of retrieving the pointer to the required object.
I have published the blog article with an interactive diagram for API object model. You can zoom, pan and click on the diagram blocks to explore the relationship. Link to blog article: Understanding API Object Model
Thanks,
Artem