MS Ads / Bing UET Q&A

Why is the Microsoft Click ID (MSCLKID) variable value containing a suffix value (ie. "-1")?

Based on our documentation and technical specifications for Microsoft Advertising, the behavior you are possibly seeing in JENTIS Previews network protocol actually a standard feature of the Microsoft Click ID (MSCLKID).

The MSCLKID is typically a 32-character GUID. Microsoft appends an extra byte (a suffix) to this ID to indicate the status of the value within a session:

• A suffix of -1 (e.g., test123-1) indicates that the value is a newly generated click ID unique to that specific session as it is observed in the current web pages URL (query parameter).

• A suffix of -0 (e.g., test123-0) indicates that the value is being reused or passed along (often seen on subsequent pages like a "Thank You" page) within the same session (the source of the MSCLKID is either a cookie or the JENTIS server-side storage, depending on the tags execution type).

This is an internal Microsoft Advertising mechanism to ensure accurate conversion tracking and session management. It is not an error caused by the JENTIS implementation, but rather how Microsoft formats the parameter when auto-tagging is enabled.