Index[SYMBOL] [A] [B] [C] [D] [E] [F] [G] [H] [I] [J] [K] [L] [M] [N] [O] [P] [Q] [R] [S] [T] [U] [V] [W] [X] [Z] x-height descriptor XFrames documents URLs XHTML 2nd authoring tools case-sensitivity in style rule elements deciding to use documents in DTDs 2nd HTML conversion software HTML vs. machine-generated content and tags, quick reference Version 1.0 and HTML 4.01 Version 1.1 2nd 3rd well- formed documents and XML, using to define XHTML Basic content-based tags core tags design document header forms images lists objects scripting stylesheets tables text structural tags XHTML documents content 2nd creating 2nd 3rd ending tags in nesting elements in XML (Extensible Markup Language) 2nd as markup metalanguage DTDs special processing directives uses for 2nd 3rd xmlns attribute, defining namespaces with |