Has there been any work down into dissecting the stuttering phenomenon into broad categories? E.g. repetitions vs hard-blocks.

Has there been any work down into dissecting the stuttering phenomenon into broad categories? E.g. repetitions vs hard-blocks. Hearing other stutterers speak is always interesting, because it highlights how differently this impediment can manifest in people, despite probably having similar root causes. Idk how else to attempt to categorize by stuttering other than by listing its defining features, so here goes: - 99% of my stuttering is just hard blocks. Literal brick walls that don't let the next word out. Oftentimes, I see these blocks coming from several words away, and if I'm quick on my feet I can substitute words around to bypass the brick wall. I also find this happens mostly on vowel sounds (particularly words that start with 'a', 'i', 'e', etc). - I'm about 97% fluent while talking to myself (common in other stutterers), but about 99.9% fluent while reading out loud something from say, a book (not as common among other stutterers I think) Anyone else's stuttering share the characteristics of my own? How would you characterize your stuttering?