If set to a non-empty string value, override the values of all the other internationalisation variables. The format of a message text source file is defined as follows. Note that the fields of a message text source line are separated by a single blank character. Any other blank characters are considered as being part of the subsequent field. Set identifiers must be presented in ascending order within a single source file but need not be contiguous.
Any string following the set identifier is treated as a comment.
This line deletes message set n from an existing message catalogue. If the message-text is empty, and a blank character field separator is present, an empty string is stored in the message catalogue. Message identifiers must be in ascending order within a single set, but need not be contiguous. Empty lines in a message text source file are ignored. The effects of lines starting with any character other than those defined above are implementation-dependent.