Custom dimension feature is a newer and lighter version of Custom Variables, it simply allows sending additional parameter to Piwik PRO, either set for the particular visit or for the particular pageview. – To learn more about scope of the Dimensions (or variables) please check this article
Setting up the dimensions
Before using Custom Dimensions you need to first define them in you settings. To do that click your username in the top right corner of the Piwik PRO (1) and choose Analytics Settings (2), then choose the Custom Dimensions from the left side menu (3).
Now, you’ll need to choose the scope for which you want to create a dimension. It can be either Action or Visit. Whichever you choose, click on the Configure a new dimension button at the bottom of scope table
Type in Name, Activate your dimension and after that hit the Create button.
In case of the Page scope you can choose to extract value of the dimension from the Page URL, Page Title or URL Parameter. You can do that the same with the Piwik PRO Tag Manager later so you can ignore that part
When you create all of the needed dimensions, note their ID numbers and proceed to the Tag Manager
Setting up tracker
Now that we have our dimensions ready we need to add them to our Piwik PRO tracker.
Open the Tag Manager and edit your standard Piwik PRO tag.
Scroll down until you’ll see line + Track Piwik Custom Domain – Click it.
Now all you need to do is insert the ID from the previous step into the Index field, and choose a variable (or preset value – whichever you prefer) that should be saved as value. Repeat the above step for all of the Dimensions and save the Tracker. Remember to publish changes afterwards!
NOTE: You can read more about creating Variables in this end-user guide.
Custom Dimensions reports are added under their name in the Analytics section under Visitors (for Visit scope) and Actions (for Action scope) reports.
By Default Piwik PRO is delivered with 5 slots for each of the dimensions scope. However, raising that limit is not a problem. Just contact us at firstname.lastname@example.org and we’ll raise it to the number you require.