What is the real correct function name?

[staticor]

I want to add a subtitle in my figure.
In the doc I found there have subtitle() and suptitle,

only later on can be used in fig.xxx().

[tacaswell]

Can you please direct questions like this to the mailing list (see http://sourceforge.net/p/matplotlib/mailman/, you will have to subscribe to post) or to stackoverflow.com ?

We tend to use gh issues more for bug reports/feature requests and less for usage questions. The mailing list and SO have much broader audiences which will increase the chances of your question getting answered.