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:

1. Define the attributes you need, and decide the attribute type and details.
2. Create the Media Attribute you need, while choosing the correct type. See: Managing Media Attribute
3. Add the Media Attribute to an Existing Media Attribute Group, or create a new Media Attribute Group.  See: Managing Media Attribute Groups  
4. 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