At INCOSE IW, Janet Singer (as ISSS VP Research and Pubs) was tasked to lead a subcommittee on describing Systems Thinking, Systems Science and Systems Approach for the INCOSE Systems Engineering Book of Knowledge. Other projects (e.g. ontology) may also be involved.
See workshop at https://sites.google.com/site/syssciwg/meetings/workshop-2012-january . If you’re interested in contributing, speak up to Janet or myself!