localizedCompare: what's the locale?

FROM : Nicko van Someren
DATE : Wed Oct 06 18:35:34 2004

The documentation for NSString's localizedCompare: says "Performs a
localized compare between the receiver and string. See Also: –
compare:options:range:locale:".  Presumably it is simply calling
compare:options:range:locale: with some predefined values for options,
an empty range and a "local" locale.  My question is where does that
locale come from?  I want to do a localised search with the
NSNumericSearch option switched on, so I need to pass in the same
locale information.

Thanks in advance,

   Nicko