Table of features that are supported by all operating systems.

POSIX: x means accessible with nl_langinfo, s means accessible with localeconv (according to X/open)
Some stuff can be used with glibc nl_lang_info  - they claim it's specified by X/Open  but that's not  what the standard seems to say

Information			NLS	Posix	.Net

Name of language	
...	Localised		x	
...	English			x
...	Abbreviated	 	x
...	Native 			x
Country code - check what iso	x
Name of country	
... 	Localised		x
... 	English			x
... 	Abbreviated		x
... 	Native			x

List item separator		x
System of measure (US or SI)	x
Positive sign			x
Negative sign			x
Positive sign position		x
Negative sign position		x

Number list item separator	n
Decimal separator		x	x
Thousands separator		x	x
Digit grouping			x
Number of fractional digits	x
Number of leading zeros 	x
Negative number formatting	x

Localised currency symbol	x	x
ISO currency designator		x
Monetary decimal separator	x
Monetary thousands separator	x
Monetary digit grouping		x
Number of digits in currency	x
ISO nbr. of digits in currency	x
Currency symbol placement (pos) x	x
Currency symbol placement (neg) x

Date separator	(don't need)	x
Time separator	(don't need)	x

Short date format string	x	n
Long date format string		x	x
Date+Time format string		x	x
Era date format string (long?)	?	x
Era date+time format string	?	x
Era time format			?	x
Era descriptions		?	x (ERA)

Short time format string	n	x (T_FMT_AMPM)
Long time format string		x	x (T_FMT)

Long date format ordering	x
Short date format ordering	x


AM designator			x	x
PM designator			x	x
24-hour or 12 hour time		x
Type of calendar		x
First day of week		x
First day of year		x
Names of weekday		x	x
Abbreviated names of weekdays	x	x
Names of months			x	x
Abbreviated names of months	x	x

Alternative digits		x	x