Background
Anchor’s origins were in a research project at ETH Zurich involving marked-point-processes. Certain data objects and algorithms found in the software borrows terminology from this subject area.
What are Marked Point Processes?
They are extensions of classical point-processes that additionally associate a mark (extra attributes) with each point produced in the process.
Consider adding an extra radius attribute to a point process, so each instance is a point and a radius. It can be geometrically interpreted as producing circles.
A more mathematical introduction can be found in Marked Point Processes by Tonglin Zhang.