What is Green Paper?

Legal Definition
In the European Union, the United Kingdom, Commonwealth, Hong Kong and the United States, a green paper is a tentative government report and consultation document of policy proposals for debate and discussion. A green paper represents the best that the government can propose on the given issue, but, remaining uncommitted, it is able without loss of face to leave its final decision open until it has been able to consider the public reaction to it. Green papers may result in the production of a white paper. They may be considered as grey literature.
-- Wikipedia
Legal Definition
Basis for consultation and debate among interested parties invited to join in a process of discussion on a specific policy area circulated as this initial-draft document. Before committing to the official policy document, called the white paper, the objective is to have general consensus. Refer to white paper.