http://www.perlmonks.org?node_id=1049081


in reply to Markup tags should be written in:

Back in the olden days when the world hadn't yet got the hots for the case-sensitive XHTML, I used to ALLCAPS the HTML tags (similar to how the examples in the W3C docs had been written) and had the attributes in CamelCase. Values, where case didn't matter, lowercase. It was a nice distinction and made it easy to read things even without source code highlighting.