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<p><code>CREATE UNIQUE INDEX</code>, <code>ALTER TABLE</code> (for referential integrity), etc., using the specific statement required by that type of database.</p>

<p>There is no universal standard as to the level of detail in such a document.</p>

<p><big>Middleware</big></p>
<p>In the construction of database applications, it can be useful to introduce an additional layer of data dictionary software, i.e. <a href="page.php?w=middleware">middleware</a>, which communicates with the underlying DBMS data dictionary. Such a "high-level" data dictionary may</p><p>
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