Lognorm Shift

Key Lognorm Shift in Van Swaption Mkt refers to the optional shift (displacement) s of the lognormal distribution towards the left associated with the setting Vol Type = Shifted Lognormal.
A positive entry s corresponds to a distribution of which the graph looks like that of a lognormal distribution, but is displaced to the left so that it is defined at all values of the x axis that are strictly greater than -s
For the user's convenience it can be set regardless of the setting of the key Vol Type, but is actually used only if Vol Type = Shifted Lognormal
If omitted, 0 is assumed.