The value of the LANG environment variable or the LC_MESSAGES category (see below).
%l
The language element from the LANG environment variable or from the LC_MESSAGES category.
%t
The territory element from the LANG environment variable or from the LC_MESSAGES category.
%c
The codeset element from the LANG environment variable or from the LC_MESSAGES category.
%%
A single % character.
An empty string is substituted for undefined values.
Path names templates defined in NLSPATH are separated by colons (':'). A leading or two adjacent colons is equivalent to specifying %N.
If the oflag argument is set to the NL_CAT_LOCALE constant, LC_MESSAGES locale category used to open the message catalog; using NL_CAT_LOCALE conforms to the -xpg4 standard. You can specify 0 for compatibility with -xpg3; when oflag is set to 0, the LANG environment variable determines the message catalog locale.
A message catalog descriptor remains valid in a process until that process closes it, or until a successful call to one of the exec(3) function.
