Contiki-NG has a group of maintainers, a subset of which constitutes the board. The maintainers are in charge of commenting on issues, keeping documentation up-to-date, reviewing and merging pull requests as per the guidelines in doc:contributing. The board, in addition, takes care of general management aspects such as organizational decisions, future directions, etc.
Neither the maintainers nor the board are set in stone. Active contributors who demonstrated high standards will be invited to join as maintainer. Conversely, maintainers who become inactive over many months will be considered for removal. The board can be dissolved whenever a majority of maintainers decide so -- they will then be responsible for selecting new board members.