XHTML 1.1 which is mainly a modularization of XHTML 1.0, is composed of 20 element modules (7 of which are submodules), including the additional Ruby Annotation Module, and two attribute modules (Server-side Image Map Module and Intrinsic Events Module).
These indicate the level of support for the given item in each engine. By default, the most recent version of the engine is implied. However, a specific version number can be listed; when this indicates full support, it's the initial version of the engine fully supporting the item.
^All style tags after the first 31 style tags are not applied. All style rules after the first 4,095 rules are not applied. On pages that uses the @import rule to continuously import external style sheets that import other style sheets, style sheets that are more than three levels deep are ignored.