I am confused about the term syntactic marker as used in The Cambridge Grammar of the English Language (CGEL), by Huddleston and Pullum.
They say that to, for, that, but, and, nor, either, neither etc. are “markers”. But they also say that ‑s, ‑es, ‑ed, ‑ing are “markers”, as well.
But I don’t understand why those are called syntactic markers. How many different types of these “markers” does English possess?
Can you please give me a clear explanation on this topic?