On a per-query basis, you can specify a key on which to sort the records and a sort direction.
<Sort Key="keyName" Direction="dirOrder"/>
Note that the attribute name and the sort order are both case sensitive.
<soapenv:Envelope
xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/">
<soapenv:Header/>
<soapenv:Body>
<Request xmlns="http://www.endeca.com/MDEX/conversation/3/0">
<Language>en</Language>
<State>
<Name>AllRecs</Name>
<RecordKind>data</RecordKind>
</State>
<RecordListConfig Id="RecordList" MaxPages="20">
<StateName>AllRecs</StateName>
<RecordsPerPage>10</RecordsPerPage>
<Page>1</ns:Page>
<Sort Key="ModelName" Direction="Ascending"/>
</RecordListConfig>
</Request>
</soapenv:Body>
</soapenv:Envelope>
The example specifies an ascending sort order based on the ModelName attribute.