I found a thread on stackexchange which suggests adding the atom:updated
element to the feed using the following code:
add_action( 'rss2_item', function() {
printf(
'<atom:updated>%s</atom:updated>', get_post_modified_time( 'D, d M Y H:i:s +0000', true )
); }
);
The element is inserted into the feed with the correct time stamp so now I just need to do some testing.
– And this is an update.
– Looks like it may need the atom date format which in PHP is Y-m-dTH:i:sP
– That has worked!