Pocketing, I had wondered if those type of buttonholes were used. I mean, you don't have to do all those stitches on them, right? Or am I thinking of a bound buttonhole?
J-Waters has clarified that he was talking about using pocketing material as a layer of interfacing. I think you were thinking of a bound buttonhole. These look just like a minature double welted pocket, and I think are made the same way (I've never attempted one). That is, put the binding material face down on the coat, sew around the slit, slit the hole open and turn the binding through. I don't know if another layer of binding is used on the back side or if the material from the front is turned under and felled down. I understand this kind of buttonhole is often found on Confederate officer's coats made in Louisiana and elsewhere in the Deep South, leading some to speculate that it's due to French or Spanish tailoring influence. Any better information on the subject would be welcome.