Prefix and term case sensitivity

A couple of questions:


 1.  Section 7.5 Step 4 and elsewhere calls for the prefix of a URI mapping to be converted to lower case. Section 6 (CURIE Syntax Definition) provides rules for determining the URI. "Otherwise, if a CURIE consists of a non-empty prefix and reference, and if there is an in-scope mapping for prefix, then the URI is created by using that mapping, and concatenating it with the reference." Should this call for the mapping of prefix to be made lower case? This certainly makes a difference if prefixes defined by @xmlns remain case sensitive, which is also an open issue.
 2.  XHTML+RDFa section 5.2 indicates that terms mapped to the XHTML Default Vocabulary to mapped to lower case. However, Base 7.4.3 does not require this in general. I presume that this a specific requirement of XHTML+RDFa, and should only be performed if the default vocabulary is that of XHTML (or other languages that include similar requirements). Is this interpretation correct? Or, should terms always be mapped to a lower case representation?

Gregg