By the GTD definition, anything you don't decide to move on, is a SomedayMaybe. The problem with that is that the S/M is not a daily review list, while the Procrastination List must be reviewed more often than weekly, of necessity, or it will automatically become a S/M, or worse, a "never".
Also, items in S/M are things you feel comfortable not doing anything about yet, while the Procrastination List reminds of things you want to move on, while not letting them get in your way right now.

I have created it in two sizes, classic and hipster (I use both). The file formatting of the classic size below is freely based on the work of hofsanoj's "Next Step List-Advanced" (great template by the way).
The main two columns are "What is it" and "Why". This template size includes a few contexts just in case my mind unfreezes and I actually make some decisions (calls, errands, at computer, WaitingFor, quadrant 1, quadrant 2, and Someday/Maybe), as well as a Date column to track how old the item is.

The hipster size below is pretty simple for lack of space, just two columns, What, and Why.
For some reason, while I am allowed to upload multiple templates, I am only allowed to upload just one preview image, so I have only added the Classic one.

I hope it is helpful to someone.