In this question, OP had included their attempts(source), but it didn't get rendered. Anyone know why?

@ThomasShelby seems like OP wrote "<" followed immediately by a non space character (actually did twice), afterwards the renderer (hope that's the word) will hide everything that is followed afterwards until it meets a space (enter or a tab of three spaces will occur) or it ends with "<".

Here's an imgur link which shows almost how it works.

So after OP wrote 0<x1 and so on, the rest didn't render.

@Zacky *or it ends with ">".

@ThomasShelby As far as I can tell, it was render after your edit. So wasn't the problem simply missing dollars.

I was wrong - it's not just missing dollars.

I have copied the OP's text in the fromatting sandbox: math.meta.stackexchange.com/revisions/25988/2

So the SE software simply understands it as HTML markup, but there is no element called <x> (and moreover, it is unfinished) .... ?

If I change that line to 0<x1<1 and 0<x2<1> (I have just added ">" at the end), the rest is shown and the part between "<" and ">" is ignored.

Somewhat related: How can I escape the less than symbol when it is next to a alphabetical character? and How can I format to show text inside “<” and “>”?

Here is the version after an edit mentioned above: math.meta.stackexchange.com/revisions/25988/3

@Zacky Actually it doesn't have to follow immediately a non space character, other things also work to hide what's after "<".

@MartinSleziak @Zacky Thanks for explaining!