ATTRIBUTE_VJS_SOURCE_PORT
constATTRIBUTE_VJS_SOURCE_PORT:"data-vjs-source-port"="data-vjs-source-port"
Indicates the ID of the physical port that the element represents when it is acting as an edge source. In some situations you might want to use the same element as a source and target, but have the data model use different ports ids. See discussion for data-vjs-port to read about how this differs from data-vjs-source-port-id
See
Advanced
Dom Attribute
Context
edge-dragging