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When one to one mapping is enabled the internal ids are used as external ids when not mapped explicitly. When this option is not enabled the id map also acts as a filter when at least one location is mapped explicitly (using for example <location>). In that case, everything that is not mapped is not imported or exported. When not one location is mapped explicitly, enableOneToOneMapping is enabled by default but is good practice to explicitly configure the xml element. Note that the filtering option for exporting does not work in combination with the export option to write separate files per location through the data export option <useExternalLocationIdAsName>.
When FEWS imports time series with enableOneToOneMapping, it uses quite some flexibility for mapping. First it tries to match exactly on location, parameter, qualifiers, ensembleId, ensembleMemberId and timeStep. But if that does not result in a match it tries to match with less, by ignoring ensembleId, ensembleMemberId, timeStep and at last qualifiers. This could cause different time series to be imported to the same time series set, for instance when two time series are imported that only differ based on a qualifier and one of the time series does not have an exact match on a configured time series set. A warning will then be logged: "Multiple time series sets found for XXX" and it may be in unclear from which time series the data will be imported. This can be prevented by adding a configured time series set that does match exactly, but if it is not desired that this data is imported, <synchLevel>9</synchLevel> can be used so the data is mapped correctly but ignored.
enableCaseInsensitivity
When case insensitivity is enabled the mapping of external to internal ID's will be case insensitive during imports.
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