LANG 

Specify a local name. 

LC_MESSAGES 

Specify a messaging locale. If specified, this overrides LANG for messages.

LC_CHARSET 

Specify a messaging character set. If specified, this selects a character set directory to search for the message object file. 

TEXTDOMAIN 

Specify the domain name of interest. The tngettext command uses TEXTDOMAIN only if you omit tngettext's domain argument.

TEXTDOMAINDIR 

Specify the path name to the message database. If present, this replaces TNHOME/usr/lib/locale/msgs.