That's quite remarkable. I can only assume that, like most people writing HTML by hand, they copy-pasted the boilerplate from some other page without really understanding it.

I can find no other references to this on Google, the best I can do is: http://xml.coverpages.org/mdml.html which links to http://xml.coverpages.org/dow-mdml-dtd20010105.txt : that refers to

<!DOCTYPE mds-results PUBLIC "-//Dow Jones//DTD MDML//EN">

The original Dow Jones page from that era according to the Internet Archive (and this is an amazing thing in itself!) just has <HTML>, no DOCTYPE. In 1997 it acquires <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN">

The DOCTYPE element technically describes the Document Type Definition (DTD). The HTML there doesn't mean it's an HTML document: it means the root element of the document is an HTML tag. The "-//Dow Jones//DTD DJ-HTML//EN" is a Formal Public Identifier, which specifies the actual DTD. The vast majority of sites don't actually guarantee their HTML is valid or even well-formed. In the grand scheme of things, this is most likely cruft left over from the early days of when the site was published and a lot of these things were more up in the air.

For a bit more detail:

https://en.wikipedia.org/wiki/Document_type_declaration#Synt...