gettext: perl-format

 
 15.3.23 Perl Format Strings
 ---------------------------
 
    There are two kinds of format strings in Perl: those acceptable to
 the Perl built-in function ‘printf’, labelled as ‘perl-format’, and
 those acceptable to the ‘libintl-perl’ function ‘__x’, labelled as
 ‘perl-brace-format’.
 
    Perl ‘printf’ format strings are described in the ‘sprintf’ section
 of ‘man perlfunc’.
 
    Perl brace format strings are described in the
 ‘Locale::TextDomain(3pm)’ manual page of the CPAN package libintl-perl.
 In brief, Perl format uses placeholders put between braces (‘{’ and
 ‘}’).  The placeholder must have the syntax of simple identifiers.