The inclusion of some functionality is also based on whether you have add-ons in addition to the base functionality. I believe that T4’s are part of the Seneric payroll add-on but is not an out of the box NAV feature. I am not sure where to find the specific localization information, I have only been able to find general information online in Microsoft documents (e.g. http://www.google.ca/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&ved=0CDUQFjAA&url=http%3A%2F%2Fdownload.microsoft.com%2Fdownload%2FB%2F4%2F5%2FB4523F10-96D2-4D07-BCAC-D5911B50329A%2FMBS_NAV_AvailabilityGuide_US.pdf&ei=D7upUtzJH8iurgHn0YDoBQ&usg=AFQjCNHQyy08qyoNdWobjxADH791UE7t0Q&sig2=Dz45hbOEiAysPm3JkBrkfg)