# Help:FAQ/Technical questions

## Technical questions

### Problem with Eqn template

"I've added a proof sequence using the {{eqn}} template, and despite my best efforts the parser barfs on it. It makes a horrendous mess that I can't work out how to clear up."

What's probably happened is that you have included instances of {{ or }} or | in your $\LaTeX$.
The MediaWiki template parser takes precedence over the MathJax one, and views {{ and }} as the beginning and end of the invocation of {{eqn}}, thus breaking the $\LaTeX$ in two. Similarly, it interprets | as the MediaWiki instruction to interpret what follows as a parameter value.
In order to get round this, you need to:
1. Put a conventional space between all instances of {{ and }} to make them { { and } }
2. Replace all instances of:
1. | with \vert
2. || and \| with \Vert, which renders as $\Vert$.
--prime mover (talk) 08:58, 8 March 2013 (UTC)

### Can't get a maintenance template to register my parameter

"I am trying to (for example) get the "explain" template to show:

{{explain|Why does $a = b$?}}

... but when it appears on the page, the "Why does $a = b$?" bit does not show."

This is because the MediaWiki template parser takes precedence over the MathJax one, and interprets your $=$ sign as being part of a parameter invocation. That is, it thinks that Why does $a is the name of the parameter being passed to the {{Explain}} template and that b$? is its value.
In order to get round this, the {{=}} template was developed, which allows you to put the $=$ sign into an invocation of the template, like so:
{{explain|Why does $a {{=}} b$?}}
This should fix it.
--prime mover (talk) 08:58, 8 March 2013 (UTC)