New Lead Activity - Meaning of primaryAttributeValueId when Source Type=List import?
What does the 'primaryAttributeValueId' value map to on new lead activities (ActivityType=12) when the 'Source Type' is 'List import'? I have seen cases where this value either matches the value in 'leadId' or it is different. For example, if I import a list from a CSV file, the value of 'leadId' and 'primaryAttributeValueId' are the same. However there are other cases that we have seen where these values are different. Under what situations is this the case and what does the value in 'primaryAttributeValueId' mean when it is different than 'leadId'?
Here is an example:
{
"id": 5839728,
"leadId": 512336,
"activityDate": "2016-10-01T16:22:19Z",
"activityTypeId": 12,
"primaryAttributeValueId": 379523,
"attributes": [{
"name": "Created Date",
"value": "2016-10-01"
},
{
"name": "List Name",
"value": "Archive 2016 Campaign.2016Forums.1096-Event"
},
{
"name": "Source Type",
"value": "List import"
}]
}