The issue I speak of is duplicate content by way of duplicate URL structures returning the same content. John goes into enough detail to make your head explode. The problem is so complicated that some engineer had to come up with a word for it that I couldn’t pronounce if I trained for a year in Tibet with monks specializing in SEO Kung Fu. Canonicalization! There I said it. Wait, that’s spelling, I still have no idea how to pronounce it.
When I first found ModX they were much like any other CMS. Claiming titles without a true understanding of what it meant. Their heading on the homepage says it all: “PHP Application Framework. Ajax CMS. SEO CMS.” Unfortunately they suffered from the same canonicalization issues as every other CMS system I have found. Fortunately their creators were willing to listen and now have a complete grasp on the issue.
I created the first version of the SEO Strict URLs plugin for ModX and the community has since taken it to a new level. With just one small plugin requiring no system edits, ModX is 100% canonicalization issue free (unless you create them yourself). All virtual files have one acceptable URL and any variation will return a 404 error header or 301 redirect to the proper version. This includes any file extension or directory (ModX calls them containers).
The SEO Strict URLs plugin is slated for inclusion in all future release downloads and hopefully a core correction so no plugin is needed in the future.
There’s a million and one things I could say about this CMS that I am in love with and a few things I’m not but this is about the SEO aspect. If your looking for a CMS or framework that works with you instead of forcing you to work with it in respect for both design and SEO, ModX is your baby.