A document type can be shared between authors in two ways:
save the document type at global level in the Document Type Association panel and distribute a zip file that includes all the files of the document type (CSS stylesheets, jar files with custom actions, etc). Each user will unzip the zip file in a subdirectory of the ${frameworks} directory and will restart the application for adding the new document type to the list of the Document Type Association panel
save the document type at project level in the Document Type Association panel and distribute both the Oxygen project file and the files of the document type (CSS stylesheets, jar files with custom actions, etc). Each user will copy the files of the document type in the subdirectory of the ${frameworks} directory that corresponds to the document type and will load the Oxygen project file in the Project view.