Looking to leverage the DCS API calls against a users ECID to send in information from our internal database. We have a stored table of ECID's. I am aware this is available for sending in against UUID's or Declaired ID's that have been synced, but this specific use case is built around the ECID.
I see in the documentation there's a field for ECID (d_mid) but I want to confirm this is possible.
Yes, it is possible to send data via DCS APIs using ECIDs.
Check this doc for more info: https://experienceleaguecommunities.adobe.com/t5/adobe-audience-manager-blogs/getting-data-in-audien...
P.S. MID and ECID is the same thing.
Additionally, you can contact Adobe client care and request for an export of all AAM UUIDs against ECIDs if Visitor ID service and AAM were implemented on your web properties.