If we change the sequence to a, b, c, 9 then 9 is no longer sharing the attribute of «letter,» but it is still a written sign. (religion-online.org)
75 percent of all traffic on the Internet is due to file sharing, with 59 percent of that file sharing attributed to people swapping video files. (slaw.ca)
I'd then share the attributes of each category. (inc.com)