Re: Doc: <lilypond> is a tag not an environment

[Werner LEMBERG]

> While translating I saw that the <lilypond> tag recognized by
> lilypond-book is called environment (as \lilypond{} in LaTeX).
> Wouldn't it be more correct to call it tag?
> 
> Here's the part of the Usage manual where HTML is discussed:
> https://gitlab.com/lilypond/lilypond/-/blob/master/Documentation/en/usage/lilypond-book.itely#L562

I think it makes sense to have uniform terms for all output formats.
In particular, 'lilypond-book' primarily addresses LaTeX, which uses
'environment'.

Looking up HTML terminology
(https://en.wikipedia.org/wiki/HTML_element) it seems you could
clarify the documentation by explaining that an LaTeX 'environment' is
called a 'container element' in HTML speak, started and ended by an
opening and closing tag, respectively.

```
<lilypond> music </lilypond>
```

On the other hand, the equivalent to a LaTeX 'command' is

```
<lilypond ...: music />
```

and seems to be called a 'void element'.

Admittedly, the used terms in the lilypond-book documentation are
sloppy.  An MR that improves it is highly welcomed :-)


    Werner