I want to know the answer to the following question:
What is the special marking that shows messages can be shared with these other five countries?
All the background I'm provided with is that "A new handling caveat, USA/AUS/CAN/GBR/NZL Five Eyes, used primarily on intelligence messages, gives an easier way to indicate that the material can be shared with Australia, Canada, United Kingdom, and New Zealand.". Is that enough to answer the question?