doc: clarify the date standard output formats

* src/date.c (usage): Use FMT rather than TIMESPEC as the parameter,
since it's simpler to understand and can be better aligned.
Give an example for the --iso-8601 output format.
Adjust the example used for the 3 standard formats to be unambiguous
with respect to day/mon ordering and use of leading zeros in the time.
Reorder the options descriptions slightly, so that the
3 standards options are together.
Indent the multi-line descriptions so that grouping is obvious.
Remove a redundant description of the --rfc-3339 format,
which is obvious in the existing example.
Separate these 3 standards options to their own translatable string
to simplify translation.
Change 'date and time' to 'date/time' in the --iso-8601 description
to be consistent with --rfc-3339 and to help avoid the implication
that the time is always output or even output by default.
Fixes http://bugs.gnu.org/20203

1 files changed, 22 insertions, 16 deletions

diff --git a/src/date.c b/src/date.c
index 65fd0fc5f..eaee8b273 100644
--- a/src/date.c
+++ b/src/date.c
@@ -132,26 +132,32 @@ Display the current time in the given FORMAT, or set the system date.\n\
       emit_mandatory_arg_note ();
 
       fputs (_("\
-  -d, --date=STRING         display time described by STRING, not 'now'\n\
-  -f, --file=DATEFILE       like --date once for each line of DATEFILE\n\
-  -I[TIMESPEC], --iso-8601[=TIMESPEC]  output date/time in ISO 8601 format.\n\
-                            TIMESPEC='date' for date only (the default),\n\
-                            'hours', 'minutes', 'seconds', or 'ns' for date\n\
-                            and time to the indicated precision.\n\
+  -d, --date=STRING          display time described by STRING, not 'now'\n\
+  -f, --file=DATEFILE        like --date; once for each line of DATEFILE\n\
 "), stdout);
       fputs (_("\
-  -r, --reference=FILE      display the last modification time of FILE\n\
-  -R, --rfc-2822            output date and time in RFC 2822 format.\n\
-                            Example: Mon, 07 Aug 2006 12:34:56 -0600\n\
+  -I[FMT], --iso-8601[=FMT]  output date/time in ISO 8601 format.\n\
+                               FMT='date' for date only (the default),\n\
+                               'hours', 'minutes', 'seconds', or 'ns'\n\
+                               for date and time to the indicated precision.\n\
+                               Example: 2006-08-14T02:34:56-0600\n\
 "), stdout);
       fputs (_("\
-      --rfc-3339=TIMESPEC   output date and time in RFC 3339 format.\n\
-                            TIMESPEC='date', 'seconds', or 'ns' for\n\
-                            date and time to the indicated precision.\n\
-                            Date and time components are separated by\n\
-                            a single space: 2006-08-07 12:34:56-06:00\n\
-  -s, --set=STRING          set time described by STRING\n\
-  -u, --utc, --universal    print or set Coordinated Universal Time (UTC)\n\
+  -R, --rfc-2822             output date and time in RFC 2822 format.\n\
+                               Example: Mon, 14 Aug 2006 02:34:56 -0600\n\
+"), stdout);
+      fputs (_("\
+      --rfc-3339=FMT         output date/time in RFC 3339 format.\n\
+                               FMT='date', 'seconds', or 'ns'\n\
+                               for date and time to the indicated precision.\n\
+                               Example: 2006-08-14 02:34:56-06:00\n\
+"), stdout);
+      fputs (_("\
+  -r, --reference=FILE       display the last modification time of FILE\n\
+"), stdout);
+      fputs (_("\
+  -s, --set=STRING           set time described by STRING\n\
+  -u, --utc, --universal     print or set Coordinated Universal Time (UTC)\n\
 "), stdout);
       fputs (HELP_OPTION_DESCRIPTION, stdout);
       fputs (VERSION_OPTION_DESCRIPTION, stdout);