Am I breaking the rules if I embed data in the questions using HTML-like markup?

Question

Inspired by this "hot" question I posted another question and answer attempting to work out an optimal and seamless methods for embedding data into questions by taking advantage of the fact that Stack Exchange accepts HTML in the questions, and therefore text such as

<undefined rubbish>

should be ignored when formatting the question for display, but still be available when editing the question.

That question was meant to be concerned only with the technical aspect, therefore was posted in MmaSE.

Now perhaps the most relevant topic is about policy, and that needs to be discussed here in Mma Meta:

1. Am I breaking the rules if I embed data in the questions using HTML-like markup?

2. What would be a good way to figure out the limit in attachment size of a question without abusing the site?

Answer 1

Ad 1.

Couldn't find anything official so let me quote R.M. with whom I agree:

I don't think there's anything wrong per se... my only thought is that we shouldn't rely on hidden HTML tags because SE is perfectly free to strip out tags that they don't need (maybe not now, but in the future). So from that pov this is rather fragile.

– R. M.♦ Apr 27 at 15:13

Ad 2.

StringLength I suppose because there is a limit of 30k characters per question/answer.

Why not restrict questions to some max length?