^I can read some CHS characters. You are correct on all counts. One of the Motorfan links goes into detail on the actual boundary between 户A/户B and 户C as does the original SH Traffic PSB linky. While the actual forbidden areas differ to that of the inner ring road, it is easier and more useful in some respects to use the inner ring road as a defacto demarcation line/boundary than having to remember the actual roads - unless one is riding the same routes fairly regularly.