Code Markup is a WordPress plugin that makes it easy to include program code samples in your posts.
The plugin allows you to quickly copy and paste code into your blog, and add HTML markup to it to emphasise certain parts of it. Normally this is not possible without a lot of fiddly manual editing.
If the code block has its lang attribute set to html or xhtml, then no tags are allowed: all tags are escaped and will display as typed. Otherwise the following tags are allowed: em strong b i ins del a span
To make the code block render as straight HTML, set the code block's "markup" attribute to "all". In this case, make sure that you have typed correct HTML!
To make the code block display exactly as typed, set the code block's "markup" attribute to "none".
To allow the default tags to be rendered as HTML, even in HTML code, set the code block's "markup" attribute to "default".