Declaration: TSpdc.Assign (Source: TSpdc): integer;
The method Assign copies the TSpdc instance specified by the parameter Source to self. The function returns a zero value if everything is OK, or -1 if the spectral descriptor cannot be copied.

Hint: In general, the statement Destination := Source; is not the same as the statement Destination.Assign(Source);. The first statement makes Destination referring to the same object as Source, whereas the second statement copies the contents of the object referenced by Source into the object referenced by Destination.