Request advise on seat foam & grommets for hog rings

Not sure I have ever seen grommets for the hog rings (although one would think they would need to have them)
Most of what I have seen is a string or metal wire sewn into the edges of the material to keep the rings from pulling out, but the rings just go through the material. (there's a name for the string, but I can't seem to come up with it)
This is how our BMW full interior recovers are, as well as the recovered seats in my Dart are done.

Maybe search Youtube.com for some instructional video's.