A user's view of the database is determined by their
profile, which contains the list of chapters that they currently
Developers may place elements of the schema into any
chapter that they choose, and that piece of the schema will be operative
or inoperative depending on whether the chapter containing it is
included or excluded from the user's profile.
Individual items and links exist in peer networks in individual
chapters. When chapters are collected together in a profile, the
items and links in each chapter simply form a wider peer network,
and chapters become transparent.
When links are created between items in different chapters, if
either the source or target of the link is not visible in the current
profile, neither is the link itself.