Searching for a Data Dictionary for SQL or Oracle I am looking for metadata specifications (data dictionary) for SQL Server and Oracle databases.

By metadata map, I mean a definitive description of what objects make up database model and their relationships (i.e. a server has 0:n databases, a table has 1:n columns, a column has 0:n constraints).

Any versions of these DBMS platforms would be useful.
I've Community Wiki'd this 

Oracle


Storage can hold multiple databases
Databases can be opened by multiple instances
Server can run run multiple instances
A server can only run a single instace for any given database
Data is stored in tablespaces
A tablespace may be made up of multiple data files
Tables/indexes/Materialized Views can be partitioned across multiple segments
A segment lives on a tablespace
A database object (table, index, stored program unit...) is owned by a user
A table may be be referenced (through a foreign key constraint) by another table, including a table owned by another user
A table may have at most one primary key constraint
A table may have zero or more unique constraints
A primary key or unique constraint is logically enforced by exactly one index (though you could have a multi-column unique constraint which is backed up by multiple unique indexes with the columns in a differing order)
An index may be unique or non-unique. A unique constraint may be enforced by a unique or non-unique index.
A table must have at least one column
Each column has a datatype (and optionally a length or precision/scale)
A trigger may relate to at most a single table. (Some triggers, such as SERVERERROR, don't relate to a table).