I was about to create a separate category for 'container' formats, but thought I would check here just in case someone had lumped them under compression. Which is what has happened. Having a 'non-compressed' category under the 'compression' category demonstrates the folly of this approach, I think!
I realise that zip and related formats conflate the two notions, but there are many, many container formats which aren't compressed. And there are some compression formats (LZW for example) that aren't container formats. I vote for splitting them but with appropriate cross-linking,