I'm not sure what you're suggesting, PHV. As far as I know, there is no reference involved - just a line of code:
Declare Sub ITMSG Lib "itmsgmod.dll" (inp1 As Double, inp2 As Double, out1 As Double, out2 As Double, out3 As Double, out4 As Double, out5 As Double)
and a subsequent call to the...