Okay, still avoiding paying for a Plex Pass in order to figure out their code, but I took a look at IceTV XMLTV format for Plex and noticed a live sport event from them looks like the below:
<programme airingID="140789207" mediaID="13016-0" start="20180909020000 +0000" stop="20180909033000 +0000" channel="2659">
<title lang="en">AFL: Game Day</title>
<desc lang="en">Hamish McLachlan hosts a weekly panel to discuss, review and preview all things AFL.</desc>
<category lang="en">Sport</category>
<category lang="en">Talk Show</category>
<category lang="en">AFL</category>
<language lang="en">English</language>
<icon src="http://images.icetv.com.au/placeholder/13016_poster.png" width="1000" height="680" />
<country lang="en">Australia</country>
<sport lang="en">AFL</sport>
<episode-num system="original-air-date">2018-09-09 10:00:00</episode-num>
<video>
<present>yes</present>
<colour>yes</colour>
<aspect>16:9</aspect>
<quality>HDTV</quality>
</video>
<premiere />
<subtitles type="teletext" />
<rating system="ACMA">
<value>PG</value>
</rating>
</programme>
They don’t include the date element either, but they add a few things that are not defined in the XMLTV DTD.
The airingID and mediaID attributes are not part of the XMLTV description document and I assume this is IceTV’s equivalent to our “dd_progid” episode numbering system.
They add a < sport > element which may have a positive impact in this case. I am assuming that sports is the only thing affected, but I have no idea what Plex is doing.
Also of note is IceTV seems to use the Premiere flag to indicate a Live event… I think I’ll use that. That is something the XMLTV is missing.