sgmljs.net Markdown is presented as an application of the SGML SHORTREF feature, which is an SGML mechanism to describe custom Wiki or other domain-specific syntax. Whereas in regular markdown it's possible to use HTML markup, in sgmljs.net Markdown it's also possible to use SGML markup and other constructs, bringing SGML's vast facilities for text organization and processing to markdown in a natural way.

sgmljs.net Markdown implements the original markdown syntax with the "fenced code blocks" and "tables" feature of GitHub-flavored markdown, and with select pandoc markdown extension features. In the remainder of this text, markdown.pl is used as a reference to John Gruber's original Markdown when discussing differences between sgmljs.net Markdown and other markdown formatters.