Field Definitions are Available Here
Collection
string (80)
The processing level class contains the level identifier and level description of the collection.
3
/ProcessingLevelId
/gmi:MI_Metadata/gmd:identificationInfo/gmd:MD_DataIdentification/gmd:processingLevel/gmd:identifier/gmd:MD_Identifier/gmd:code/gco:CharacterString
Identification Information (ECHO)