Named wrapper environment with ltx:block and ltx:inline-block

myblocks.sty.ltxml

# -*- mode: Perl -*-
use strict;
use warnings;
use LaTeXML::Package;

DefEnvironment("{namedwrap}{}", "<ltx:inline-block class='#1'>#body</ltx:inline-block>");
DefEnvironment("{namedblock}{}", "<ltx:block class='#1'>#body</ltx:block>");

1;

test.html

<article class="ltx_document">
  <div id="p1" class="ltx_para">
    <div class="ltx_block sample-value">
      <p class="ltx_p">Hello World!</p>
    </div>
  </div>
  <div id="p2" class="ltx_para">
    <span class="ltx_inline-block sample-value">
      <span class="ltx_p">Hello World!</span>
    </span>
  </div>
</article>

test.tex

\documentclass{article}
\usepackage{myblocks}
\begin{document}

\begin{namedblock}{sample-value}
  Hello World!
\end{namedblock}

\begin{namedwrap}{sample-value}
  Hello World!
\end{namedwrap}

\end{document}

Generated via:

latexmlc test.tex --format=html --whatsout=fragment