The list author says: "M/M erotica/romance books with varying levels of light BDSM--from simple spanking to light bondage and whipping.
I have another list with BDSM books that are heavier--from moderate to very graphic (for beginners, anyway). The last book on this list is (in my opinion) not as heavy/graphic as the first book on that list; the two lists are designed to basically run together."
"Light--bondage, spanking. The D/s in this story is unplanned and informal, and it catches one of the guys by surprise (because he's never thought about it before and is shocked to discover how much he likes it).
"Fairly light--light bondage (although most of it is internal--having to keep himself still without the help of tools), spanking, one scene of whipping. Most of the focus here is on submission as a result of spoken commands.