Branch Metrics, Inc.

marketing_cloud_visitor_id property

According to Branch’s documentation (archived), the $marketing_cloud_visitor_id property contains the Adobe Marketing Cloud Visitor ID. The Marketing Cloud Visitor ID uniquely identifies a user across apps/domains as well as devices (archived).

mixpanel_distinct_id property

According to Branch’s documentation (archived), the $mixpanel_distinct_id property contains the Mixpanel Distinct ID. According to Mixpanel’s documentation (archived):

Distinct ID is Mixpanel’s identifier used to uniquely track a user in the system. […]

The purpose of Distinct ID is to provide a single, unified identifier for a user across devices and sessions. When two events have the same value of distinct_id, they are considered as being performed by one unique user. If the Distinct ID on two events are two different values, they will be considered as coming from two separate users.

segment_anonymous_id property

According to Branch’s documentation (archived), the $segment_anonymous_id property contains the Segment Anonymous ID. According to Segments’s documentation (archived), their IDs “[specify] a customer identity that you can reference across the customer’s whole lifetime”. The Anonymous ID is to be used in “cases where you don’t actually know who the user is according to your database, but you still want to be able to tie them to traits, events, or page views“.