Shareholder and board meeting dates.
1 - WSH began capturing meeting type on September 22, 2012. They backfilled meeting type for some history, 2007 through 2012, concentrating on F1000 and S&P500 companies.
2 - An exclamation point/mark means WSH have either removed the company from their coverage list or the ticker symbol was reused. For example, ticker MAG used to be Magnetek Inc., now it’s MAG Silver Corp.