Android install referrer : pcampaignid=APPU_2

Seems that it's related to a campaign, Just decompose key as p campaign id. However, After looking deeper into docs, I didn't find any official documentation that mentions this. It seems garbage value because it doesn't make any sense and not related to the referral. The library is officially developed by Google, We can only aspect a perfect answer from them. Well, there are so many communities in varieties of language over the internet, where this question has been asked but not with a single response at all. It is highly possible that it's a campaign id of google's itself with is linked to the library code/this page where the library docs hosted. However, these are all assumptions missing the evidence.

Also, I suggest going through Collecting the Mobile Device IDs list, Where the remarketing is done through the device id. here in case, google must be using analytics to identify device id and referrals. So the chances are higher for pcampaignid=APPU_2_......... as a google's internal campaign id.

Note: If you search about this, You'll find the same question asked in all the different languages everywhere. This is the only satisfactory description so far.