I don't think that Hermes ever manufactured its own slugs, and given that there were at least six suppliers (that I'm aware of) of slugs used by Hermes, you won't find an across-the-board "naming convention". ​In other words, you need to match the markings of the slug to its actual manufacturer's typeface list.

​The S6 slug you're asking about should be one of the Setag pica typefaces (there were a number of them). A S7 in a Hermes would be a Setag elite.
 

Georg's website is a great resource for Hermes information and I have a lot of respect for his efforts. I hadn't read that page before, which includes slug information for licenced Hermes models too (he's used one of my photos for them), but the page is missing Ransmayer & Rodrian data. I suspect he's fully aware of their use, but I'll send him an email just to be sure.

S DP= Director Pica
It could be deduced, but I thought I'd add it to your list.
 

My Hermes 3000 has S TE on the slugs. By extrapolation I'm going to say that's a TECHNO ELITE typeface. That's good to know information. I have been a little unsure of that for awhile. Thanks sys700. You have a nice collection.

For example, it was only through studying numerous photos that I discovered that the Script version of the H3000 does not have a 3/4 symbol. Instead, it has a numeral 1 key in its place. I've seen variations with square bracket keys, and two different Deluxe cases (one with chrome trim, one painted). Would be really nice to document all the variations in one database file.