<div dir="ltr"><div class="gmail_default" style="color:rgb(51,102,255)">Hi Georg,</div><div class="gmail_default" style="color:rgb(51,102,255)">One of the easiest way to achieve correct MathML tag for this is to use below tex4ht cfg on your MWE:</div><div class="gmail_default" style="color:rgb(51,102,255)"><br></div><div class="gmail_default" style="color:rgb(51,102,255)"><font face="monospace, monospace">%-------------------------------------------------------------------</font></div><div class="gmail_default" style=""><div class="gmail_default" style=""><font color="#3366ff" face="monospace, monospace">% htlatex <tex> <cfg></font></div><div class="gmail_default" style=""><font color="#3366ff" face="monospace, monospace">\RequirePackage{amssymb} % used for \mathbb</font></div><div class="gmail_default" style=""><font color="#3366ff" face="monospace, monospace">\RequirePackage{bm} % used for \boldsymbol</font></div><div class="gmail_default" style=""><br></div><div class="gmail_default" style=""><font color="#3366ff" face="monospace, monospace">\Preamble{xhtml,mathml}</font></div><div class="gmail_default" style=""><font color="#3366ff" face="monospace, monospace">\Configure{VERSION}{}</font></div><div class="gmail_default" style=""><font color="#3366ff" face="monospace, monospace">\Configure{DOCTYPE}{\HCode{<!DOCTYPE html>\Hnewline}}</font></div><div class="gmail_default" style=""><font color="#3366ff" face="monospace, monospace">\Configure{HTML}{\HCode{<html>\Hnewline}}{\HCode{\Hnewline</html>}}</font></div><div class="gmail_default" style=""><font color="#3366ff" face="monospace, monospace">\Configure{@HEAD}{}</font></div><div class="gmail_default" style=""><font color="#3366ff" face="monospace, monospace">\Configure{@HEAD}{\HCode{<meta charset="UTF-8" />\Hnewline}}</font></div><div class="gmail_default" style=""><font color="#3366ff" face="monospace, monospace">\Configure{@HEAD}{\HCode{<meta name="generator" content="TeX4ht</font></div><div class="gmail_default" style=""><font color="#3366ff" face="monospace, monospace">(<a href="http://www.cse.ohio-state.edu/\string~gurari/TeX4ht/">http://www.cse.ohio-state.edu/\string~gurari/TeX4ht/</a>)" />\Hnewline}}</font></div><div class="gmail_default" style=""><font color="#3366ff" face="monospace, monospace">\Configure{@HEAD}{\HCode{<link</font></div><div class="gmail_default" style=""><font color="#3366ff" face="monospace, monospace"> rel="stylesheet" type="text/css"</font></div><div class="gmail_default" style=""><font color="#3366ff" face="monospace, monospace"> href="\expandafter\csname aa:CssFile\endcsname" />\Hnewline}}</font></div><div class="gmail_default" style=""><font color="#3366ff" face="monospace, monospace">\Configure{@HEAD}{\HCode{<script type="text/javascript"\Hnewline</font></div><div class="gmail_default" style=""><font color="#3366ff" face="monospace, monospace">src="<a href="http://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS-MML_SVG">http://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS-MML_SVG</a>"\Hnewline</font></div><div class="gmail_default" style=""><font color="#3366ff" face="monospace, monospace">></script>\Hnewline}}</font></div><div class="gmail_default" style=""><font color="#3366ff" face="monospace, monospace">\Configure{@HEAD}{\HCode{<style type="text/css">\Hnewline</font></div><div class="gmail_default" style=""><font color="#3366ff" face="monospace, monospace"> .MathJax_MathML {text-indent: 0;}\Hnewline</font></div><div class="gmail_default" style=""><font color="#3366ff" face="monospace, monospace"></style>\Hnewline}}</font></div><div class="gmail_default" style=""><font color="#3366ff" face="monospace, monospace">\begin{document}</font></div><div class="gmail_default" style=""><font color="#3366ff" face="monospace, monospace">\EndPreamble</font></div><div class="gmail_default" style=""><font color="#3366ff" face="monospace, monospace"><br></font></div><div class="gmail_default" style=""><span style="color:rgb(51,102,255);font-family:monospace,monospace">\def\mathbbm#1{\boldsymbol{\mathbb{#1}}}</span><br></div><div class="gmail_default" style=""><div class="gmail_default" style="color:rgb(51,102,255)"><span style="font-family:monospace,monospace">\endinput</span><br></div></div><div style="color:rgb(51,102,255)"><div class="gmail_default" style="color:rgb(34,34,34)"><div class="gmail_default" style="color:rgb(51,102,255)"><font face="monospace, monospace">%-------------------------------------------------------------------</font></div><div class="gmail_default"></div></div></div><div style="color:rgb(51,102,255)"><br></div><div style="color:rgb(51,102,255)">But still I am only able to see normal blackboard font through browser, while the MathML is <mstyle mathvariant="bold"><mi>ℤ</mi></mstyle>.</div><div style="color:rgb(51,102,255)"><br></div><div style="color:rgb(51,102,255)">Regards</div><div style="color:rgb(51,102,255)">Jagath</div></div></div><div class="gmail_extra"><br><div class="gmail_quote">On 25 August 2015 at 00:14, Hans Georg Schaathun <span dir="ltr"><<a href="mailto:georg+tex@schaathun.net" target="_blank">georg+tex@schaathun.net</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><span class="">On Mon, Aug 24, 2015 at 08:32:58PM +0200, Michal Hoftich wrote:<br>
> could you please provide some sample document? This depends on your<br>
> input, in particular on used fonts. We can map LaTeX font symbols to<br>
> unicode values, so it shouldn't be impossible to get blackboard letters<br>
> without some custom macros.<br>
<br>
</span>Of course here is an example:<br>
\documentclass{scrartcl}<br>
\usepackage{bbm}<br>
\def\Z{\mathbbm{Z}}<br>
\begin{document}<br>
$\Z$<br>
\end{document}<br>
<br>
I am not sure what you have in mind. You are right that there is are<br>
Unicode characters for blackboard bold letters. A common solution<br>
in LaTeX would however code it as a blackboard bold font. I have not<br>
checked the implementation of the bbm package, so I do not know what<br>
that one does.<br>
<br>
Either way, I am not hellbent on using bbm; any solution which works<br>
in both PDF and XML output is fine.<br>
<span class="HOEnZb"><font color="#888888"><br>
<br>
--<br>
:-- Hans Georg<br>
</font></span></blockquote></div><br></div>