How to call GetTapeParameters?

I am trying to use GetTapeParameters to get the media parameters.  When I use the code segment below, I get a MORE_DATA error with 32 returned in tape_parms_size.  The size of tape_parms is 25.  If I change the tape_parms type to TAPE_GET_DRIVE_PARAMETERS which is 32
bytes then the call will work.  However,  if I don't use the
TAPE_GET_MEDIA_PARAMETERS type then I don't know which bytes represent the block size.  Why is the GET_TAPE_MEDIA_INFORMATION call returning
a structure that is larger than TAPE_GET_MEDIA_PARAMETERS and how do I
know the layout for the structure that it is returning?  I am using Windows NT 4.0 with an Exabyte EXB-8505 8mm tape drive connected to an Adaptec  AHA-2940AU SCSI controller.

TAPE_GET_MEDIA_PARAMETERS tape_parms;
DWORD tape_parms_size;

status = GetTapeParameters(hTape, GET_TAPE_MEDIA_INFORMATION,
&tape_parms_size, &tape_parms);
pdoughtyAsked:
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msmitsCommented:
(this is all from memory, as my code is at home and I can't get to it until friday night)

I noticed the same when using the Tape API. There are more locations in the win32 API where the returned size is bigger than the size advertised in the struct definition in the header files. I have learned to ignore the aditional information returned, as they are usually all zero's.
This is also what I do with these extra bytes in my program using the GetTapeParameters function.

BTW. you example code doesn't set the tape_parms_size variable. From your explanation I assume you do so...

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