'Research liaison'

I've read a Marketing Document recently. It's about Marketing Research.

'A research brief should include:

1. Brief number
2. Date
3. Client Group
4. Client contact
5. Research Liaison
6. Project name/ description
7. Market(s)
8. Referent brand(s)
9. Consumer segment(s)
10. Background
11. Project objective(s)
12. Action Standard(s)
13. Presentation/ reporting requirements
14. Timing
15. Stimulus materials
16. Brief acceptance"

Can you please help me explain the terms 'client contact, research liaison, brief acceptance'

Thanks in advance.