You must be knowledgeable of the subscription protocols. I wrote a concept for an aggregator, but it would need a custom value with each post. Do you know if th

You must be knowledgeable of the subscription protocols. I wrote a concept for an aggregator, but it would need a custom value with each post. Do you know if there is room for that? It's a simple rating by the posting user (e.g. 7 out of 10, you could even just post it with the text like so: [7/10] But that's a little confusing.) The one other question: If I had this rating, could I sort all posts from the last year by rating? Or is the efficient look-up of posts tied to time and it's hard to scan for ratings through a year worth of posts?