meta: various issues/questions about TES.

Hi there!

We recently used TES during the St. Jude Biohackathon ([code](https://github.com/stjude-biohackathon/kids24-team15)) to build a new workflow execution engine. As part of that, we also developed the [`tes`](https://github.com/stjude-rust-labs/tes) crate. During that exercise, I had several questions about the TES specification.

I'm going to create an issue for each of these, but I wanted to have this meta issue just to keep track of all of the conversations and/or if there are bigger picture thoughts to discuss.

- #206
- #207
- #208
- #209
- #210

This is a meta issue for TES specification questions rather than a standalone change. Start by reviewing linked issues #206 through #210 and their discussions; completion is not defined here beyond tracking those conversations and any broader specification decisions.

Written by the indexing model from the issue text.