A friend of mine, close to NOAA, says they don't even know how/when/why the term was meant to be used or numbered. It apparently surfaced for the first time in early September, relative to discovery from a Sat passover and at one time the same designator was used for storms in both the Pacific & Atlantic. Some thinking is that "Invest" is a flag the comp's setup for NOAA staff to "Investigate" - but who knows.