<!-- doc/src/sgml/isn.sgml -->

<sect1 id="isn" xreflabel="isn">
 <title>isn &mdash; data types for international standard numbers (ISBN, EAN, UPC, etc.)</title>

 <indexterm zone="isn">
  <primary>isn</primary>
 </indexterm>

 <para>
  The <filename>isn</filename> module provides data types for the following
  international product numbering standards: EAN13, UPC, ISBN (books), ISMN
  (music), and ISSN (serials).  Numbers are validated on input according to a
  hard-coded list of prefixes; this list of prefixes is also used to hyphenate
  numbers on output.  Since new prefixes are assigned from time to time, the
  list of prefixes may be out of date.  It is hoped that a future version of
  this module will obtain the prefix list from one or more tables that
  can be easily updated by users as needed; however, at present, the
  list can only be updated by modifying the source code and recompiling.
  Alternatively, prefix validation and hyphenation support may be
  dropped from a future version of this module.
 </para>

 <para>
  This module is considered <quote>trusted</quote>, that is, it can be
  installed by non-superusers who have <literal>CREATE</literal> privilege
  on the current database.
 </para>

 <sect2 id="isn-data-types">
  <title>Data Types</title>

  <para>
   <xref linkend="isn-datatypes"/> shows the data types provided by
   the <filename>isn</filename> module.
  </para>

  <table id="isn-datatypes">
   <title><filename>isn</filename> Data Types</title>
   <tgroup cols="2">
    <colspec colname="col1" colwidth="1*"/>
    <colspec colname="col2" colwidth="2*"/>
    <thead>
     <row>
      <entry>Data Type</entry>
      <entry>Description</entry>
     </row>
    </thead>

    <tbody>
     <row>
      <entry><type>EAN13</type></entry>
      <entry>
       European Article Numbers, always displayed in the EAN13 display format
      </entry>
     </row>

     <row>
      <entry><type>ISBN13</type></entry>
      <entry>
       International Standard Book Numbers to be displayed in
       the new EAN13 display format
      </entry>
     </row>

     <row>
      <entry><type>ISMN13</type></entry>
      <entry>
       International Standard Music Numbers to be displayed in
       the new EAN13 display format
      </entry>
     </row>
     <row>
      <entry><type>ISSN13</type></entry>
      <entry>
       International Standard Serial Numbers to be displayed in the new
       EAN13 display format
      </entry>
     </row>
     <row>
      <entry><type>ISBN</type></entry>
      <entry>
       International Standard Book Numbers to be displayed in the old
       short display format
      </entry>
     </row>
     <row>
      <entry><type>ISMN</type></entry>
      <entry>
       International Standard Music Numbers to be displayed in the
       old short display format
      </entry>
     </row>
     <row>
      <entry><type>ISSN</type></entry>
      <entry>
       International Standard Serial Numbers to be displayed in the
       old short display format
      </entry>
     </row>
     <row>
      <entry><type>UPC</type></entry>
      <entry>
       Universal Product Codes
      </entry>
     </row>
    </tbody>
   </tgroup>
  </table>

  <para>
   Some notes:
  </para>

  <orderedlist>
   <listitem>
    <para>ISBN13, ISMN13, ISSN13 numbers are all EAN13 numbers.</para>
   </listitem>
   <listitem>
    <para>EAN13 numbers aren't always ISBN13, ISMN13 or ISSN13 (some
    are).</para>
   </listitem>
   <listitem>
    <para>Some ISBN13 numbers can be displayed as ISBN.</para>
   </listitem>
   <listitem>
    <para>Some ISMN13 numbers can be displayed as ISMN.</para>
   </listitem>
   <listitem>
    <para>Some ISSN13 numbers can be displayed as ISSN.</para>
   </listitem>
   <listitem>
    <para>UPC numbers are a subset of the EAN13 numbers (they are basically
    EAN13 without the first <literal>0</literal> digit).</para>
   </listitem>
   <listitem>
    <para>All UPC, ISBN, ISMN and ISSN numbers can be represented as EAN13