The place this mostly comes up is on internet forms. Lots of forms will ask for your name in full width character then again in katakana in half-width. They'll ask for address in full width but postal code and phone number in half width.
The place this mostly comes up is on internet forms. Lots of forms will ask for your name in full width character then again in katakana in half-width. They'll ask for address in full width but postal code and phone number in half width.