+ <para>
+ &odr; is a basic mechanism for representing an
+ ASN.1 type in the C programming language, and for implementing BER
+ encoders and decoders for values of that type. The types defined in
+ the &asn; module generally have the prefix <literal>Z_</literal>, and
+ a suffix corresponding to the name of the type in the ASN.1
+ specification of the protocol (generally Z39.50-1995). In the case of
+ base types (those originating in the ASN.1 standard itself), the prefix
+ <literal>Odr_</literal> is sometimes seen. Either way, look for
+ the actual definition in either <filename>z-core.h</filename> (for the types
+ from the protocol), <filename>odr.h</filename> (for the primitive ASN.1
+ types).
+ The &asn; library also provides functions (which are, in turn,
+ defined using &odr; primitives) for encoding and decoding data values.
+ Their general form is
+
+ <funcsynopsis>
+ <funcprototype><funcdef>int <function>z_<replaceable>xxx</replaceable></function></funcdef>
+ <paramdef>ODR <parameter>o</parameter></paramdef>
+ <paramdef>Z_<replaceable>xxx</replaceable> **<parameter>p</parameter></paramdef>
+ <paramdef>int <parameter>optional</parameter></paramdef>
+ <paramdef>const char *<parameter>name</parameter></paramdef>
+ </funcprototype>
+ </funcsynopsis>
+ (note the lower-case "z" in the function name)
+ </para>
+
+ <note>
+ <para>
+ If you are using the premade definitions of the &asn; module, and you
+ are not adding new protocol of your own, the only parts of &odr; that you
+ need to worry about are documented in section
+ <link linkend="odr-use">Using ODR</link>.
+ </para>
+ </note>
+