You can access questions with tags by link construction:
http://stackoverflow.com/questions/tagged/[tag1] or [tag2] or [tag3]
But when I combine a lot of tags I get an error 400 (invalid URL). In my case the URL length was 755 characters.
But when I use the link
http://stackoverflow.com/feeds/tag?tagnames=[tag1] or [tag2] or [tag3]&sort=newest
then the page is loaded, even though I used the same big set of tags (and this time we have 768 characters).
When I pass the link to my RSS reader (with
%20 instead of a space)
all data was properly loaded with no errors (908 characters this time).
Is there some bug/limitation to the length of the first link construction (http://stackoverflow.com/questions/tagged/%5Btags%5D) that does not apply to second method (http://stackoverflow.com/feeds/tag?tagnames=%5Btags%5D)?