The APIdocs for all the enums.

PermissionFlags

Implementation:

enum PermissionFlags {
    None     = 0,
    Read     = (1 << 0),
    Write    = (1 << 1),
    Execute  = (1 << 2),
    Private  = (1 << 3),
    Shared   = (1 << 4)
};

Comments:

The flags for permissions on mapped memory regions