The handling of the "locale" attribute in the JSF core taglib tags
<f:convertDateTime> and <f:convertNumber> is inconsistent with each other and
with the handling of the "locale" attribute in the <f:view> view-root tag.
For <f:convertDateTime>, the description mandates that the implementation must
pass any string value as the first arg to the two-arg Locale constructor, and
pass the empty string as the second arg.
For <f:convertNumber>, the tld docs imply that string values are not supported
at all, but the sun javaserverfaces api implementation does allow literal
strings that are treated the same way as for <f:convertDateTime>.
In both cases, it would be more useful and consistent if String values were
treated as references to locale "names" using the same syntax as for the
<f:view> locale attribute (ie, allow language-country-variant type strings).
Placing support for a standard "locale" attribute in the <f:converter> tag may
be a good way to provide consistent behaviour for both <f:convertDateTime>,
<f:convertNumber>, and any user supplied custom converters.