ConvertToDate
A variant value
The date to use if the variant is not a valid date
nze(Null, #1/1/1970#) => #1/1/1970# nze("1/1/1980") => #1/1/1980# nze(#1/1/1990#) => #1/1/1990# nze("notadate") => #1/1/1970#