Modify Feed

As WordPress content isn’t the only thing to change on my website I have modified my wp-rss2.php to include my so called “Today’s Recommendation”. If the recommendation is newer than my latest journal entry then the pubDate is set to my recommendations date/time (strange: it should be 00:00:00 +0100 but isn’t, however the last-modified time is…I am using the same variable here…)

I have also modified the wp-blog-header.php to keep the last-modified info on track.

As my recommendations didn’t show up in Bloglines I set the expires-date to a past date and then it worked in Bloglines. At least I assume it was due to this change.

Then I tested in FeedDemon and it didn’t update my recommendations, however Journal Entries work fine.

Now I’ve got a bunch of questions:
– Is it wrong to set the expires date (in the past)?
– What is ETag?
– What does the xmlrpc.php do?
– What is the code in the wp-blog-header.php commented as “// Support for Conditional GET” all about?

Link to my feed https://www.kingcosmonaut.de/feed/rss2/

Cheers, Sebastian