Get compatibility mode which affects the way calculations are done by all the extension functions.
</para>
</refsect1>
<refsect1role="returnvalues">
&reftitle.returnvalues;
<para>Returns the compatibility mode id which can be identified by <linkxmlns="http://docbook.org/ns/docbook"linkend="trader.constants">TRADER_COMPATIBILITY_*</link> series of constants.