The expiration switch (which has no heading) is also a toggle. It determines
whether a particular option expiration is displayed in a skew window. Set to
on, the respective expiration is rendered in white, and an asterisk indicates
the switch is on. Set to off, the asterisk disappears, and the record is
rendered in gray.
Apart from the obvious effect of making a particular option expiration display
in a skew window, the expiration switch has another significant roles: it
determines whether an option expiration is included in the skew curve calculation.
Further, if you turn on the last expiration in the table, the
The Expiration Switch