Looking for industry standard and/or tool to represent and export RDBMS metadata Do you know of an industry standard that is designed to describe the metadata contents of a relational database (or part of it, such as tables, columns, etc.)?

Do you know if a tool exists that does export the metadata of any of the top 5 RDBMS tools in any format such as XML (without having to type in DDL in the syntax of particular database)?

Thank you.
If you want a set of views that are "common" across database vendors (Oracle, MySQL, PostgreSQL, ...), there are the INFORMATION_SCHEMA views. 

They are supposed to be a common standard across vendors (exactly how true I don't know). In SQL Server (versions >= 2000) you access them via [INFORMATION_SCHEMA].{view_name}, where {view_name} is any one of: 


CHECK_CONSTRAINTS,
COLUMN_DOMAIN_USAGE,
COLUMN_PRIVILEGES,
COLUMNS,
CONSTRAINT_COLUMN_USAGE,
CONSTRAINT_TABLE_USAGE,
DOMAIN_CONSTRAINTS,
DOMAINS,
KEY_COLUMN_USAGE,
PARAMETERS,
REFERENTIAL_CONSTRAINTS,
ROUTINE_COLUMNS,
ROUTINES,
SCHEMATA,
TABLE_CONSTRAINTS,
TABLE_PRIVILEGES,
TABLES,
VIEW_COLUMN_USAGE,
VIEW_TABLE_USAGE,
VIEWS.


Here's some tips on how to make use of them: INFORMATION_SCHEMA.TABLES | mssqltips.com.