DOM Level 0: what was implemented for JavaScript in Netscape 3/IE3
DOM Level 1, a W3C Standard
DOM Level 2, a W3C Standard
DOM Level 3: Several Working Drafts:
Document Object Model (DOM) Level 3 Core Specification
Document Object Model (DOM) Level 3 Views and Formatting Specification
Document Object Model (DOM) Level 3 Abstract Schemas and Load and Save Specification Version 1.0
Document Object Model (DOM) Level 3 Events Specification Version 1.0