Does content always have to be in chronological order in an RSS feed?

I run a site where users can upload content that is displayed in a gallery where other users can sort and 开发者_如何学Pythonfilter that content. While implementing RSS feeds, I was wondering how common it was for an RSS feed to display items in an order that's different from chronological. For example, displaying content by Most Views first. This could be useful for someone wanting to keep tabs on trending content. How do RSS readers handle this, since most RSS feeds are ordered chronologically?

It is not required, but it is helpful.

Additionally you can add the pubDate element to each item to help feed aggregators understand how items relate/fall chronologically against each other.

<pubDate> is an optional sub-element of <item> which is supposed to represent the date that item was posted or published at the source.

Some client RSS readers may not read the pubDate element at all and will just display items as it is read. Others will, and if items appear out of date order re-arrange them in the feed aggregator to display as necessary.

RSS works great for tracking items as they are added, such as a news site or blog. It's not so good for publishing stats or leaderboard type data.