(gettext.info.gz) PO Files
3 The Format of PO Files
The GNU `gettext' toolset helps programmers and translators at
producing, updating and using translation files, mainly those PO files
which are textual, editable files. This chapter explains the format of
A PO file is made up of many entries, each entry holding the relation
between an original untranslated string and its corresponding
translation. All entries in a given PO file usually pertain to a
single project, and all translations are expressed in a single target
language. One PO file "entry" has the following schematic structure:
#| msgid PREVIOUS-UNTRANSLATED-STRING
The general structure of a PO file should be well understood by the
translator. When using PO mode, very little has to be known about the
format details, as PO mode takes care of them for her.
A simple entry can look like this:
msgid "Unknown system error"
msgstr "Error desconegut del sistema"
Entries begin with some optional white space. Usually, when
generated through GNU `gettext' tools, there is exactly one blank line
between entries. Then comments follow, on lines all starting with the
character `#'. There are two kinds of comments: those which have some
white space immediately following the `#' - the TRANSLATOR COMMENTS -,
which comments are created and maintained exclusively by the
translator, and those which have some non-white character just after the
`#' - the AUTOMATIC COMMENTS -, which comments are created and
maintained automatically by GNU `gettext' tools. Comment lines
starting with `#.' contain comments given by the programmer, directed
at the translator; these comments are called EXTRACTED COMMENTS because
the `xgettext' program extracts them from the program's source code.
Comment lines starting with `#:' contain references to the program's
source code. Comment lines starting with `#,' contain flags; more
about these below. Comment lines starting with `#|' contain the
previous untranslated string for which the translator gave a
All comments, of either kind, are optional.
After white space and comments, entries show two strings, namely
first the untranslated string as it appears in the original program
sources, and then, the translation of this string. The original string
is introduced by the keyword `msgid', and the translation, by `msgstr'.
The two strings, untranslated and translated, are quoted in various
ways in the PO file, using `"' delimiters and `\' escapes, but the
translator does not really have to pay attention to the precise quoting
format, as PO mode fully takes care of quoting for her.
The `msgid' strings, as well as automatic comments, are produced and
managed by other GNU `gettext' tools, and PO mode does not provide
means for the translator to alter these. The most she can do is merely
deleting them, and only by deleting the whole entry. On the other
hand, the `msgstr' string, as well as translator comments, are really
meant for the translator, and PO mode gives her the full control she
The comment lines beginning with `#,' are special because they are
not completely ignored by the programs as comments generally are. The
comma separated list of FLAGs is used by the `msgfmt' program to give
the user some better diagnostic messages. Currently there are two
forms of flags defined:
This flag can be generated by the `msgmerge' program or it can be
inserted by the translator herself. It shows that the `msgstr'
string might not be a correct translation (anymore). Only the
translator can judge if the translation requires further
modification, or is acceptable as is. Once satisfied with the
translation, she then removes this `fuzzy' attribute. The
`msgmerge' program inserts this when it combined the `msgid' and
`msgstr' entries after fuzzy search only. Fuzzy Entries.
These flags should not be added by a human. Instead only the
`xgettext' program adds them. In an automated PO file processing
system as proposed here the user changes would be thrown away
again as soon as the `xgettext' program generates a new template
The `c-format' flag tells that the untranslated string and the
translation are supposed to be C format strings. The `no-c-format'
flag tells that they are not C format strings, even though the
untranslated string happens to look like a C format string (with
In case the `c-format' flag is given for a string the `msgfmt'
does some more tests to check to validity of the translation.
msgfmt Invocation, c-format Flag and
Likewise for Objective C, see objc-format.
Likewise for Shell, see sh-format.
Likewise for Python, see python-format.
Likewise for Lisp, see lisp-format.
Likewise for Emacs Lisp, see elisp-format.
Likewise for librep, see librep-format.
Likewise for Scheme, see scheme-format.
Likewise for Smalltalk, see smalltalk-format.
Likewise for Java, see java-format.
Likewise for C#, see csharp-format.
Likewise for awk, see awk-format.
Likewise for Object Pascal, see object-pascal-format.
Likewise for YCP, see ycp-format.
Likewise for Tcl, see tcl-format.
Likewise for Perl, see perl-format.
Likewise for Perl brace, see perl-format.
Likewise for PHP, see php-format.
Likewise for the GCC sources, see gcc-internal-format.
Likewise for Qt, see qt-format.
Likewise for Boost, see boost-format.
It is also possible to have entries with a context specifier. They
look like this:
#| msgctxt PREVIOUS-CONTEXT
#| msgid PREVIOUS-UNTRANSLATED-STRING
The context serves to disambiguate messages with the same
UNTRANSLATED-STRING. It is possible to have several entries with the
same UNTRANSLATED-STRING in a PO file, provided that they each have a
different CONTEXT. Note that an empty CONTEXT string and an absent
`msgctxt' line do not mean the same thing.
A different kind of entries is used for translations which involve
#| msgid PREVIOUS-UNTRANSLATED-STRING-SINGULAR
#| msgid_plural PREVIOUS-UNTRANSLATED-STRING-PLURAL
Such an entry can look like this:
#: src/msgcmp.c:338 src/po-lex.c:699
msgid "found %d fatal error"
msgid_plural "found %d fatal errors"
msgstr "s'ha trobat %d error fatal"
msgstr "s'han trobat %d errors fatals"
Here also, a `msgctxt' context can be specified before `msgid', like
The PREVIOUS-UNTRANSLATED-STRING is optionally inserted by the
`msgmerge' program, at the same time when it marks a message fuzzy. It
helps the translator to see which changes were done by the developers
on the UNTRANSLATED-STRING.
It happens that some lines, usually whitespace or comments, follow
the very last entry of a PO file. Such lines are not part of any entry,
and will be dropped when the PO file is processed by the tools, or may
disturb some PO file editors.
The remainder of this section may be safely skipped by those using a
PO file editor, yet it may be interesting for everybody to have a better
idea of the precise format of a PO file. On the other hand, those
wishing to modify PO files by hand should carefully continue reading on.
Each of UNTRANSLATED-STRING and TRANSLATED-STRING respects the C
syntax for a character string, including the surrounding quotes and
embedded backslashed escape sequences. When the time comes to write
multi-line strings, one should not use escaped newlines. Instead, a
closing quote should follow the last character on the line to be
continued, and an opening quote should resume the string at the
beginning of the following PO file line. For example:
"Here is an example of how one might continue a very long string\n"
"for the common case the string represents multi-line output.\n"
In this example, the empty string is used on the first line, to allow
better alignment of the `H' from the word `Here' over the `f' from the
word `for'. In this example, the `msgid' keyword is followed by three
strings, which are meant to be concatenated. Concatenating the empty
string does not change the resulting overall string, but it is a way
for us to comply with the necessity of `msgid' to be followed by a
string on the same line, while keeping the multi-line presentation
left-justified, as we find this to be a cleaner disposition. The empty
string could have been omitted, but only if the string starting with
`Here' was promoted on the first line, right after `msgid'.(1) It was
not really necessary either to switch between the two last quoted
strings immediately after the newline `\n', the switch could have
occurred after _any_ other character, we just did it this way because
it is neater.
One should carefully distinguish between end of lines marked as `\n'
_inside_ quotes, which are part of the represented string, and end of
lines in the PO file itself, outside string quotes, which have no
incidence on the represented string.
Outside strings, white lines and comments may be used freely.
Comments start at the beginning of a line with `#' and extend until the
end of the PO file line. Comments written by translators should have
the initial `#' immediately followed by some white space. If the `#'
is not immediately followed by white space, this comment is most likely
generated and managed by specialized GNU tools, and might disappear or
be replaced unexpectedly when the PO file is given to `msgmerge'.
---------- Footnotes ----------
(1) This limitation is not imposed by GNU `gettext', but is for
compatibility with the `msgfmt' implementation on Solaris.
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