You can create an IS document type based on the contents of a source JSON object.

When creating an IS document type from a JSON object, keep in mind that Designer displays the location of the source JSON object in the Source URI property. Designer also sets the Linked to source property to true which prevents any editing of the document type contents. To edit the document type contents, you first need to make the document type editable by breaking the link to the source. For information about allowing editing of elements derived from a source, see Allowing Editing of Derived Elements.