I want to know the answer to the following question:
What was one of the issues with setting a single HDTV standard?
All the background I'm provided with is that "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.". Is that enough to answer the question?
Answer: yes