Merge e2e2675d99 into d55d1f423d

Only one operation is used: `%`
The formatting option sequence like `05d` is called a "specification".

README.md

@@ -534,7 +534,7 @@ The `-o` option allows users to indicate a template for the output file names.
 
 **tl;dr:** [navigate me to examples](#output-template-examples).
 
-The basic usage is not to set any template arguments when downloading a single file, like in `youtube-dl -o funny_video.flv "https://some/video"`. However, it may contain special sequences that will be replaced when downloading each video. The special sequences may be formatted according to [python string formatting operations](https://docs.python.org/2/library/stdtypes.html#string-formatting). For example, `%(NAME)s` or `%(NAME)05d`. To clarify, that is a percent symbol followed by a name in parentheses, followed by formatting operations. Allowed names along with sequence type are:
+The basic usage is not to set any template arguments when downloading a single file, like in `youtube-dl -o funny_video.flv "https://some/video"`. However, it may contain special sequences that will be replaced when downloading each video. The special sequences may be formatted according to [Python printf-style string formatting](https://docs.python.org/3/library/stdtypes.html#printf-style-string-formatting) ([Python 2 documentation here](https://docs.python.org/2/library/stdtypes.html#string-formatting)). For example, `%(NAME)s` or `%(NAME)05d`. To clarify, that is a percent symbol followed by a name in parentheses, followed by a formatting specification. Allowed names along with sequence type are:
 
  - `id` (string): Video identifier
  - `title` (string): Video title