The article is a good start. I can add what's helpful in my experience: Core RBAC includes users, assignments, roles, permissions, operations, objects, and sessions.
For a system that implements RBAC, the objects can represent information containers e.g. files/directories within an operating system, locks on columns/rows/tables within a database management system, tags on resources within an application, exhaustible system resources such as storage or CPU cycles, etc.
RBAC can get you a long way, but there comes a time when you need even more granular permissions that are context aware (eg is the user an owner of the thing they are accessing and are they accessing from an internal IP address)
I think that's what the article was describing as ABAC, and explicitly declared (paraphrasing, not quoting) "temporarily out of scope because this blog post is long enough".
But yeah, ephemeral/contextual stuff can be really important too, though getting as far as a decent RBAC system does tend to buy you a lot over most statuses quo.
For a system that implements RBAC, the objects can represent information containers e.g. files/directories within an operating system, locks on columns/rows/tables within a database management system, tags on resources within an application, exhaustible system resources such as storage or CPU cycles, etc.
The ANSI RBAC spec is here: http://www.list.gmu.edu/journals/tissec/ANSI+INCITS+359-2004...