Infrastructure

From

https://repository.dataone.org/software/cicore/trunk/cn/d1_cn_index_processor/src/main/resources/application-context-isotc211-base.xml

The current XPath for the keyword field pulls out:

//gmd:identificationInfo/gmd:MD_DataIdentification/gmd:descriptiveKeywords/gmd:MD_Keywords/gmd:keyword/gmx:Anchor/text() | 
//gmd:identificationInfo/gmd:MD_DataIdentification/gmd:descriptiveKeywords/gmd:MD_Keywords/gmd:keyword/gco:CharacterString/text()

ISO also defines MD_DataIdentification/gmd:topicCategory which is defined as "The main theme(s) of the dataset." and is required (recommended) when describing a dataset. It's conditional, and repeatable. An example from a PANGAEA doc is

...
            <ns0:topicCategory>
                <ns0:MD_TopicCategoryCode>geoscientificInformation</ns0:MD_TopicCategoryCode>
            </ns0:topicCategory>
        </ns0:MD_DataIdentification>

I think it's improve recall to include in our keywords list. It appears to be a controlled vocabulary so we could even make more direct use of it. The controlled vocabulary appears to be (From the MI_Metadata workbook):

Domain:
- farming
- biota
- boundaries
- climatologyMeteorolgyAtmosphere
- economy
- elevation
- environement
- geoscientificInformation
- health
- imageryBaseMapsEarchCover
- intelligenceMilitary
- inlandWaters
- location
- oceans
- planningCadastre
- society
- structure
- transportation
- utilitiesCommunicationgeoscientificInformation, health, imageryBaseMapsEarchCover, intelligenceMilitary, inlandWaters, location, oceans, planningCadastre, society, structure, transportation, utilitiesCommunication

Both NCEI and PANGAEA make use of this field in their ISO docs.