- A primary group or the primary group?
- What is a/the primary group?
Thanks, but the this still doesn't explicitly say which primary group is used. The primary group of the specified message? A(nother) primary group?
More in general, what does "Message group the message belongs to" mean? Are there multiple options and what are the effects? If any message group of the message is fine, saying "A message group" would help, but we'd still have to explain how to choose among the multiple options.