How does Excel enumerate the Names collection?

We're getting spreadsheets from overseas offices with named ranges that we
cannot access by name, nor delete, rename or hide... Not even when I
enumerate the names collection, or loop though it by ordinal number:

For each MyName in Thisworkbook.Names
MyName.delete
Next MyName

or the alternative:

For i = Thisworkbook.Names.Count to 1 Step - 1
Thisworkbook.Names(i).Delete
Next i


As soon as either loop hits the offending item in the collection, VBA raises
the error "That name is not valid".

Inspecting the names collection using the 'Insert; Names...' dialog from the
worksheet menubar reveals that the name contains non-standard characters
which display as odd squiggles and squares on a UK- or US-locale PC. Possibly
they are umlauts, accented vowels, or copied from Cyrillic documents.

Changing the locale to Sweden, Germany or Japan doesn't help. (Japan was a
wild guess - we know it's the wrong language, but the codepage is so large
that surely there's no such thing as an invalid character...).

All suggestions welcome*

Also... Some idea of how Excel actually stores that collection would be
interesting. Surely it's got some kind of internal ordinal; I can't believe
that it's indexed by hashing the unicode string from the name.


* The suggection 'Nuke the site from orbit' has been carefully considered
but was found to be impracticable for reasons of health & safety.