Title

Page title may be used if no title is provided

Context

These (up to 20) characters can provide an extra bit of context to the URL if you want to utilise it (you don't have to). The text is appended to the URL. e.g. "stationx_shortener" would produce two URLs you can share (if 1234 was the short code produced):
http://stnx.at/1234
and
http://stnx.at/1234/stationx_shortener