The "<case:upper>" and "<case:lower>" container tags convert
all HTML tags in their body either to upper or lower case. Alternatively
there is a useful variant: Adding the "global" attribute while loading this
include file leads to a global case conversion, i.e. "#use wml::std::case
global=upper" just converts all HTML tags of the finally generated page to
upper case.
Internally this include file uses the "<tagconv>" container tag
provided by HTMLfix (pass 7).