If you are using the Experience Cloud ID Service then the visitor ID will be the "mid" value. More information about unique visitor IDs can be found at Identifying Unique Visitors. While using the Adobe debugger, I've seen some organizations with both the Analytics Visitor ID (the "aid") and Experience Cloud Visitor ID appear.
You should be able to capture values in the data collection query parameters without using Adobe DTM. I imagine that Tealium will have documentation.
I assume there will be existing visitors on your site; if the MID implementation isn't in place, all those visitors are identified using s_vi cookie. Going forward with just the MID will cause a break in the visitor activity as those visitors will start getting identified using MID as a new visitor; essentially causing visitor inflation. That requires you to enable Grace Period for the organization as that will ensure you have both AID and MID without causing any visitor inflation.
That said, Experience Cloud ID isn't replacing Analytics Visitor ID. If you are just starting using Analytics, it's sufficient to just have MID. If you are already using Analytics without MID, you will need both.
If you are using Adobe DTM you can set up a Page Load Rule that populates a variable, such as an s.eVar, with a value linked to a Data Collection Query Parameter (Data Collection Query Parameters).
For example, you could set s.eVarX to capture the Experience Cloud ID, which uses the "mid" parameter.
Set up the variable in Admin Console. Make sure that it's enabled, and not which eVar number you are using.
Log into Adobe DTM and click on the Rules item in the ribbon above where the tools are listed.
On the Rules page, click on Page Load Rules in the left menu. This takes you to the Page Load Rules page.
On the Page Load Rules page, click "Edit" next to the Global Page Load Rules. This takes you to the Edit Page Load Rule page.
On the Edit Page Load Rule page, open the Adobe Analytics accordion menu.
From the drop down menu in the eVars section, select eVarX (this is the eVar you activated in step 1). Select the "set as" radio button, and in the blank space type in D=mid. Click the "Save eVar" button.
You should now see the eVar added in the list. It will look like this: eVarX="D=mid".
You can also follow the steps above to capture the Analytics visitor ID, which uses the "aid" parameter.
By default, these IDs aren't available in Reports & Analytics or Analysis Workspace. You can, however, capture them in a custom variable like an evar or a prop and access the details in reports. There are several built-in methods (Methods ) that can be used to retrieve these visitor IDs and capture them in a variable, like getMarketingCloudVisitorID returns the MID or Experience Cloud Visitor ID.
Though you may find these visitor IDs in Data Warehouse using the dimension Experience Cloud Visitor ID and Visitor ID.
Thank you! Do you have any ready examples of how I could use this data in reporting or workspace? Are there pre-made reports available or do I have to do some customization i.e. Custom Visitor ID's/Imports to make it actionable?