ndow from airdate.</p>
</dd>
<dt>network_rank</dt><dd><p>An integer denoting the episode's weekly ranking within
network (note that the networks changed for series 8 and later).</p>
</dd>
<dt>channels_rank</dt><dd><p>An integer denoting the episode's weekly ranking
across all channels.</p>
</dd>
<dt>bbc_iplayer_requests</dt><dd><p>Number of BBC iPlayer requests (note: not
available for all series, and only for series that aired on the BBC).</p>
</dd>
<dt>us_season</dt><dd><p>An integer denoting US season (<