Used to describe a function with a const cv-qualifier.
This element is present when the function has a const cv-qualifier . This has two mandatory attributes; name and value (see example below).
See ISO/IEC 14882:2003(E) 7.1.5.1 The cv-qualifiers [dcl.type.cv]
Given this code:
struct X { void g() const; };
Then function g would have the cxxFunctionConst element:
<cxxFunctionConst />
If the mandatory attributes are present they must be set thus:
<cxxFunctionConst name="const" value="const" />