Adjustment of addressing of flight plan messages

From 0000 (UTC) on 8 OCT 2020, Viet Nam:

     - Change location indicators of Ha Noi FIR (from VVVV to VVHN) and Ho Chi Minh FIR (from VVTS to VVHM),

     - Adjustment of addressing of flight plan messages: Refer to Viet Nam AIP, item ENR 1.11.The details are here.

     - Updating list of AFTN/AMHS addresses for Viet Nam aviation: Refer to AIC A04/20. The details are here.