DMP segments are no longer supported as a separate segment type. These segments are now created as User segments. If you previously created such segments, their type will be automatically changed to User during the process of saving any changes, without any loss of functionality.
Besides traffic events, there are DMP events (or performance events) reflecting what a user did while visiting the page. DMP events reflect: ad and content recommendation impressions and clicks, the time of a visual object being within the browser view, a confirmation of a user's participation in an on-line quiz etc. Tracking such events is often referred to as user engagement tracking.
A DMP event will always be related to a pageview event both in time and space. This facilitates interesting traffic queries such as "How many users saw our latest ad campaign in the online newspaper between date A and date B?".
Action events (so-called custom DMP events used in addition to standard traffic events) can be used to create segments both through API and through Advanced mode on a Segment builder page.
To create a DMP segment, open the Segment Builder form: Segments→Create→DMP segment.
The Name and Base filters fields are required. DMP segments support only Advanced mode now, so the mode button is disabled.
It is also recommended to add some meaningful description in the Description area.