Is array syntax using square brackets in URL query strings valid?

Question

Is it actually safe/valid to use multidimensional array synthax in the URL query string?

http://example.com?abc[]=123&abc[]=456

It seem

Answer 1

I'd ideally like to comment on Ethan's answer really, but don't have sufficient reputation to do it.

I'm not sure that the relevant part of the WHATWG URL standard is being referenced here. I think the correct part might be in the definition of a valid URL-query string, which it describes as being composed of URL units that themselves are formed from URL code points and percent-encoded bytes. Square brackets are listed within URL code points and thus fall into the percent-encoded bytes category.

Thus, in answer to the original question, multidimensional array syntax (i.e. using square brackets to represent array indexing) within the query part of the URL is valid, provided the square brackets are percent encoded (as %5B for [ and %5D for ]).