AFAIK, Access doesn't have a built-in function named dproduct(). if you're
seeing it in a database that somebody else built, then it's probably a
custom function. for anyone to even *guess* at what the function does,
you'll have to paste the complete function code into your post. even then,
we may not be able to figure it out, for various reasons - for instance, a
function may call another sub or function whose purpose is unknown.
the expression
=dproduct()
suggests that the function returns a value, and the return value is being
displayed in an unbound textbox in a form or report.
hth