I apologize that this is not question about GTFS-RT or it has been discussed in the past.
To avoid unnecessary processing of stale 'static' GTFS Schedule dataset, I need to find out when a GTFS Schedule dataset was published or last updated.
In some cases, I can check the time stamp of the zip file, but that doesn't work in other cases.
The GTFS Schedule standard does specify a feed_info.txt file, which can be used but it's an optional file and I don't find it in sources I have to deal with.
Thanks,
David