What characters can one use in a URL?

I have an application that takes all the parameters in the url like this: /category/subcategory/sub-subcategory. I want to be able to give out extra parameters at the end of the URL, like page-2/order-desc. This would make the whole URL into cat/subcat/sub-subcat{delimiting-character}page-2/order-desc.

My question is: what characters could I use as {delimiting-character}. I tend to prefer ":" as I know for sure it will never appear anyplace else but I don't know if it would be standard compliant or at least if it will not give me problems in the future.

As I recall vimeo used something like this: vimeo.com/video:{code} but they seem to have changed this.