Custom Dimensions and Custom Variables in Custom Reports
Currently, Custom Reports do not feature its own Custom Variables and Custom Dimensions editor, but all dimensions and variables defined in Analytics Settings will automatically become available for use in Custom Reports.
Custom Variables and Custom Dimensions can be used as filters and as dimensions in all report types. They can be found in Dimensions section in the right sidebar when creating or editing the report. Active Custom Dimensions are represented by green blocks with Custom Dimension’s name and scope. Inactive or unconfigured Custom Dimensions are represented by green blocks with their slot and scope. Both active and inactive Custom Variables are also represented by green blocks with their slot and scope.
Custom Variables in opposite to custom dimensions don’t have human-friendly names because multiple keys or values can be set in one slot. There’s no good way to choose which key or value should be used as a human-friendly name.
The difference from Piwik PRO Standalone: In Custom Reports, Custom Variables and Dimensions on session level store only the last tracked value across all events in the session. This is different from Piwik PRO Standalone, where some reports would use the value that was set in session at the moment when an event (e.g. a conversion) was tracked.