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Note: When iterating over entities or metadata (for either entity or association building), the "$" sign is relative to the iterator, not the document (eg the metadata object being looped over). However when iterating over metadata fields that are strings, then the above document-level referencing is still valid, or "$value"/"${value}" can be used to reference the value itself.
Note: The $ sign can be escaped as ${$}.
Document updates and metadata
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