You might try looking in Access Help for the 'nz' function (but I can never find anything in Access help...)
In any case, the 'nz' function returns the value of its first parameter if that first parameter is not null; if the first parameter is null, then it returns the value of the second parameter.
It is similar to the COALESCE function in SQL (which Access doesn't support), but COALESCE is a bit more powerful. COALESCE returns the first non null value in its argument list, and it can have many arguments, whereas 'nz' is limited to only two values.
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