<literal>YES</literal> if the attribute is possibly nullable,
       <literal>NO</literal> if it is known not nullable.
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>data_type</structfield> <type>character_data</type>
      </para>
      <para>
       Data type of the attribute, if it is a built-in type, or
       <literal>ARRAY</literal> if it is some array (in that case, see
       the view <literal>element_types</literal>), else
       <literal>USER-DEFINED</literal> (in that case, the type is
       identified in <literal>attribute_udt_name</literal> and
       associated columns).
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>character_maximum_length</structfield> <type>cardinal_number</type>
      </para>
      <para>
       If <literal>data_type</literal> identifies a character or bit
       string type, the declared maximum length; null for all other
       data types or if no maximum length was declared.
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>character_octet_length</structfield> <type>cardinal_number</type>
      </para>
      <para>
       If <literal>data_type</literal> identifies a character type,
       the maximum possible length in octets (bytes) of a datum; null
       for all other data types.  The maximum octet length depends on
       the declared character maximum length (see above) and the
       server encoding.
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>character_set_catalog</structfield> <type>sql_identifier</type>
      </para>
      <para>
       Applies to a feature not available in <productname>PostgreSQL</productname>
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>character_set_schema</structfield> <type>sql_identifier</type>
      </para>
      <para>
       Applies to a feature not available in <productname>PostgreSQL</productname>
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>character_set_name</structfield> <type>sql_identifier</type>
      </para>
      <para>
       Applies to a feature not available in <productname>PostgreSQL</productname>
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>collation_catalog</structfield> <type>sql_identifier</type>
      </para>
      <para>
       Name of the database containing the collation of the attribute
       (always the current database), null if default or the data type
       of the attribute is not collatable
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>collation_schema</structfield> <type>sql_identifier</type>
      </para>
      <para>
       Name of the schema containing the collation of the attribute,
       null if default or the data type of the attribute is not
       collatable
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>collation_name</structfield> <type>sql_identifier</type>
      </para>
      <para>
       Name of the collation of the attribute, null if default or the
       data type of the attribute is not collatable
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>numeric_precision</structfield> <type>cardinal_number</type>
      </para>
      <para>
       If <literal>data_type</literal> identifies a numeric type, this