cpp/chrono/local t/formatter

Specialization of std that defines formatting rules for a std.

@1@ If, or a modified variant of  is used, a std is thrown.

@2@ The function returns a value of unspecified type that holds the local time, offset, and time zone abbreviation. When an object of this unspecified type is formatted, if  is used, it is replaced with  widened to  if  is not null; otherwise a std is thrown. If or a modified variant thereof is used, an offset of  will be formatted if  is not null; otherwise a std is thrown.

std is usually not directly accessed, but is used through formatting functions.