This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 110d. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.
[Voted into WP at March, 2010 meeting as document N2993.]
6.3 [basic.def.odr] paragraph 1 says,
No translation unit shall contain more than one definition of any variable, function, class type, enumeration type or template.
This says nothing about references. Is it permitted to define a reference more than once in a single translation unit? (The list in paragraph 5 of things that can have definitions in multiple translation units does not include references.)
Notes from the September, 2008 meeting:
The CWG expressed interest in an approach that would define “variable” to include both objects and references and to use that for both this issue and issue 633.
Proposed resolution (October, 2009):
This issue is resolved by the resolution of issue 633.