Advantage of becoming a Chartered Marine Scientist?

[buoy]

Just read a job posting for a MetOcean analyst that requires that applicants 'have achieved or are working towards chartered status'. If this rings a bell, can you please answer:
* For US marine scientists (PhD in Oceanography), what organizations grant chartered status?
* What is usually involved (costs, testing, interview, etc) to obtain chartered status?
* What opportunities would chartered status give? In other words why do people seek it?

Thanks for any insights.