5 digit channels

I am wondering what the 5 digit channels are and if they are available anywhere.  

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I was looking at the channel listings for my area in Seattle and found that it listed 5 digit channels starting with 20100 and ending with 37360.  The channels listed were all national channels but no local channels. 

What is interesting that the list of channels is from a Comcast website but the channels are not available on my X1 box. I also asked about them at the Comcast office and they had not heard of any 5 digit channels.  

So the question being asked is does anyone at Comcast have any idea about these 5 digit channels.