linked to, linked by

SIOs contain information about sources of inspiration used by the author. Such links, I name linked to are useful to trace the history of the document.
Those elements linked by a SIO, becomes part of it, as roots. They may be other SIOs, or more conventional elements: DOIs, URIs, persons referenced by their vCard, or even references to objects outside the Internet.

The relation between two SIOs may become linked to/linked by strengthening their relation, each one referring to the other; such a relation may be build up by updates of the SIOs during a 'discussion' on a topic.

linked to and linked by will help building threads over the Net on particular subjects, helping identify the history of the thread as well as the contributors to the discussion. Some digital identification of the authors should be used to avoid the expected spammers of the system.