"in parallel" in algorithm headers can be confusing

[domenic]

What is the issue with the HTML Standard?

Sometimes we have algorithms where the entire algorithm runs in parallel. Often, instead of writing the algorithm as

To do X:

1. Perform the following steps in parallel:
   1. ...
   2. ...
   3. ...
   4. ...

we write

To do X, perform the following steps in parallel:

1. ...
2. ...
3. ...
4. ...

However, this can be confusing. It's easy to visually miss the in-parallelness of the steps.

Should we consider moving to the former style, even though it's a bit ugly?

Cases of this I found in the spec:

• https://html.spec.whatwg.org/#rel-icon:in-parallel
• https://html.spec.whatwg.org/#updating-the-document:in-parallel
• https://html.spec.whatwg.org/#destroying-documents:in-parallel
• https://html.spec.whatwg.org/#sse-processing-model:in-parallel
• https://html.spec.whatwg.org/#worker-processing-model:in-parallel

/cc @domfarolino

[annevk]

I think this also applies to "switching" and maybe some other things we sometimes inline.

If it makes it harder to read for folks I'm not opposed to inline less. And generally we probably should as we also try to put more in the algorithm header such as types and often return types (although return types don't apply to in parallel of course).

[TallTed]

"In parallel" has a common meaning in English, which does not match the intended meaning here.

"Run the following steps in parallel" would usually mean, "run each of these steps in parallel with the others", not "run these steps as a sequence, in parallel with any other actions, sequences, functions, etc."

The whole Parallelism section needs some revision, such that run this list of steps in parallel (which implies with each other) is no longer used to mean run these actions in series, in parallel with actions not in this list.

I discovered this issue while trying to address a confusing section of FedCM.