Declaration: LoadSpdcs(FName: string): integer;
Loads the spectral descriptors from the file FName. If the path is omitted in the filename, the SPDC file is loaded from the default spectral descriptor directory. The function returns the following error codes:
 0 .... everything OK, descriptors are loaded into SpecDC[] structure
-1 .... mismatch of type of spectral descriptors, descriptors are loaded anyway (after confirmation by the user)
-2 .... no descriptors are loaded after user denied to load them
-3 .... no descriptors loaded due to a file which does not contain descriptors
-4 .... no descriptors loaded, file is empty

Hint: When spectral descriptors are loaded from the disk the spectral groups of the descriptors are reassigned in order to cope with multisensor datasets which may use different spectral group numbers for the same spectroscopic method. Each spectral descriptor will be assigned to the spectrum which matches both the spectral type and the order of derivative.