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All date/datetime fields should be the localtime for the location where/when the activity occured. xs:dateTime fields should be sent in in ISO 8601 format with the timezone information. If any time component isn’t recorded in the source system please set it to 0.
ASCII or Unicode encodings are preferred. Any other encodings must be indicated in the XML header and consistently applied throughout the document - a common issue with PV XML feeds was that the document as a whole claimed to be ASCII but individual sections would be in CP-1252.
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