The additional fields allow you to add up to three additional fields
to the index. These fields can be included in the output (if you use
the XML output style), sorted on, and searched on. They are populated
with the Data from Field settings (here).
Name - specifies the name of the additional field. It also
specifies element that will hold the field contents if it is output in
XML. The name must be a valid XML element name (may contain only
alnum or -_ and must start with a letter or _).
Type - specifies the internal storage type for the additional
field. Anything can be stored as Text, but if you want to do
numeric or date comparisons (such as sorting), you have to use an
appropriate data type.
Searchable - specifies whether this additional field is directly
searchable. This is done with an additional URL parameter that is
separate from the normal query. Please see the
Additional Fields section of Procedures and Examples,
here, for more details.
Sortable - specifies whether you allow sorting by this
additional field. This is done with the order search
parameter. See the Sorting section of Additional Fields,
here, for more details.
Output - specifies whether this field should be included with
the output for XML results. Note that this ONLY refers to XML output,
none of the "stock" results styles will include additional fields. If
you want an additional field to show up in your search results, you
must set Output to Y for the field, use the
XSL StylesheetResults Style, and customize the stylesheet to
display the element for the Additional Field.
Note that once Additional Fields are created and used, changing
their order or Type may alter other settings that use them,
such as Data from Field (here),
Index Fields (here) or
Compound Index Fields (here).