<field-of-search>
  <classification-national country="US"><text>435234</text></classification-national>
</field-of-search>

technical-data/field-of-search

Field of search indicates the classes/subclasses the examiner searched when examining the patent.

Element	INID	Description (delivered unformatted, either as single items or as ranges, as received from the USPTO)

Element	INID	Description (delivered unformatted, either as single items or as ranges, as received from the USPTO)
classification-ipc	58	IPC Classes
classifications-ipcr	58	IPCR Classes
classification-national	58	US Classes
classifications-cpc		CPC Classes
classification-locarno		Locarno Classes

technical-data field-of-search