Using the Znode Dynamic Schema capabilities you are able to create custom Attributes for your Media in the DAM.
The general process for this is:
Define the attributes you need, and decide the attribute type and details.
Create the Media Attribute you need, while choosing the correct type. See: Managing Media Attribute
Add the Media Attribute to an Existing Media Attribute Group, or create a new Media Attribute Group. See: Managing Media Attribute Groups
Then add the group to one of the Existing Media Attributes families (Image, Video, Audio, or File) See: Managing Media Attribute Families
Media Custom Groups and Attributes - Where do they show?
DAM > Media Explorer > choose a media item