Query: When did ITU-R start trying to work towards setting a single international HDTV standard?
Context: In 1983, the International Telecommunication Union's radio telecommunications sector (ITU-R) set up a working party (IWP11/6) with the aim of setting a single international HDTV standard. One of the thornier issues concerned a suitable frame/field refresh rate, the world already having split into two camps, 25/50 Hz and 30/60 Hz, largely due to the differences in mains frequency.