In a general sense, client compatibility is supported on a minimum release (usually what is known as the terminal or last release for older products). In other words, a higher-level client can work with a lower-level database. This configuration will most often see a performance boost as well as other known client-specific issues resolved by upgrading the client before the database. The clients in the following list that have an asterisk (*) will have little to no issues with a single version down-level database, others have a comment related to the support:
JDBC, JDK—Application specific
Precompilers—Application specific
Export/import or data pump—MOS article, very strict guidelines
Database links*
32/bit to 64/bit—SQL*Plus, C, Cobol, database link
PL/SQL features compatibility—New release features will be associated with the lowest version client
Features availability—New release features will be associated...