Tvheadend

I use a program called zap2xml to generate the tv_grab_file.xmltv used by TVHeadEnd to import the program listings. Very often a program listing will include a tag like <new /> or <previously-shown /> - here is an example of two shows with the tags:

        <programme start="20160110193000 -0500" stop="20160110210000 -0500" channel="C6pbs.zap2it.com">
                <title lang="en">Masterpiece Classic</title>
                <sub-title lang="en">Downton Abbey Season 6 on Masterpiece</sub-title>
                <desc lang="en">Downton Abbey is threatened.</desc>
                <episode-num system="dd_progid">EP01088332.0163</episode-num>
                <video>
                        <aspect>16:9</aspect>
                        <quality>HDTV</quality>
                </video>
                <previously-shown />
        </programme>
        <programme start="20160110210000 -0500" stop="20160110220000 -0500" channel="C6pbs.zap2it.com">
                <title lang="en">Masterpiece Classic</title>
                <sub-title lang="en">Downton Abbey Season 6 on Masterpiece</sub-title>
                <desc lang="en">Wedding plans hit a snag.</desc>
                <date>20160110</date>
                <episode-num system="dd_progid">EP01088332.0164</episode-num>
                <video>
                        <aspect>16:9</aspect>
                        <quality>HDTV</quality>
                </video>
                <new />
        </programme>

My question is, does TVHeadEnd actually read these tags into its database and is there any way to select a program based upon that tag when setting up a DVR AutoRec Entry? I am using HTS Tvheadend 4.0.8 and if there is a way to do it, I don't see it. The obvious goal would be to automatically record only the new shows and skip the ones tagged as previously shown. Note that not all programs have these tags but most of the major network shows do.

If TVHeadEnd will not do this at present then is there some other way to accomplish this that I'm overlooking? I suppose I could submit a feature request but my previous track record with feature requests has not been too good (they tend to get closed rather quickly for one reason or another) so before I go that route I'd like to make absolutely sure that something like this doesn't already exist in TVHeadEnd and I'm just not seeing it.