SGML (Standard Generalized Markup Language)

Definition: ISO standard for describing and defining markup languages

Key Features

• Tags: Wrapped in angle brackets (<tag>) that wrap content
• Attributes: Part of tags (<tag attribute="value">)
• Content: Information inside tags

Characteristics

• Very flexible: Allows poorly written markup to still work
• No strict structure: Can define tags however you want
• Complex parsing: Parser must infer and make best guesses
• Optional closing tags: Can open tags without closing them

Common Subsets

• XML (including XHTML)
• HTML
• OED (Oxford English Dictionary markup language)

XML (Extensible Markup Language)

Etymology: Called XML (not EML) because it was developed in the 90s when X's were considered cool

Core Principles

• Strictly hierarchical: Tags can be nested inside one another