SGML isn't that complex. If you know the XML subset of SGML, there are only a few additional concepts to learn (mostly markup minimization which is designed to

SGML isn't that complex. If you know the XML subset of SGML, there are only a few additional concepts to learn (mostly markup minimization which is designed to greatly simplify the directly authored form of a text document such that you can write markdown-like syntax, with the canonical/internal form being exactly the same as an XML parser would see it). I'll give you that the official ISO standard spec sucks to the point of being incomprehensible; but then most markup-related specs, including the HTML 5 spec, do. This is what Eliot Kimber (or was it another HyTime editor?) has to say about it (on an admittedly not so well-known topic even by markup standards): > Why can't people understand the SGML Extended Facilities as written and as standardized by the ISO? > ISO standards are very hard to understand because they describe very technical things in an abstruse techno-legal vocabulary and reduced-redundancy style. In short, despite having great things to say, even the deathless prose of the HyTime standard tends to be unreadable and, quite frankly, to suck as informative literature. (I'm a co-editor of it; may God have mercy on us.)