6. The method of claim 1, wherein the primary document address specification includes the first protocol and a first network address, and the secondary document address specification includes the second protocol and a second network address, and the first network address is different from the second network address.
6. The method of claim 1, wherein the primary document address specification includes the first protocol and a first network address, and the secondary document address specification includes the second protocol and a second network address, and the first network address is different from the second network address. 7. The method of claim 6, wherein retrieving supplementary data pertaining to the Web document by using the secondary document address specification comprises retrieving a second Web document that includes supplementary data pertaining to the Web document.