Yes you can! Unlike a Time Period Form, to which you can only add measures, it is possible to add both events and measures to an Event Period form.
You must first add an event to the event period, after which you can add measures to the event. These measures will appear as columns in the event form, much like how the configured attributes appear as columns.
The only restriction is that the measure/s that you are adding must have the same event context as the event to which you add them.
In a time period form, the measures that are added are displayed as rows and each column represents the value of the measure for a specific time period.
In an event period form, event periods are displayed as rows, and measures that are added will display as columns, where the value of the measure displayed is for the event period.
In the case of a manual measure that has been added to an event form, the user is able to capture a value for the event period.
When an event period is first created, the Flow Engine has to create all the time slices for any measures that have that event as context. While it is doing this, the event period will already display in the event form, but it is not possible to edit the value of the measures until after the Flow Engine has created all the time slices.
During this time that the event period value is not editable, a black border will appear around the selected cell, indicating that one cannot yet capture a value.
The value that is captured against a measure in an event period form is the event period value and not associated with any single time period (e.g. minutely, hourly, daily, etc). The Flow Engine will "distribute" the value entered across all the time slices that comprise the event period, based on the time slice aggregation method that was configured when the event was added as context to the measure.