1992 SIPP Topical Module 5 data doesn't seem to match its .ddf file

1992 Full Panel File produces "file SIPP92FP.DAT fails CRC check" when unzipped.

What is a CRC check?  
From http://www.securityfocus.com/archive/104/305271/2003-01-03/2003-01-09/0

   A CRC check is a very simple check originally designed to check
   the transmission of bit-serial data in an environment where there
   is a risk of noise affecting the data. The characteristics of
   such noise is that it tends to be "bursty", affecting short
   sequences of bits. A CRC check can be implemented cheaply in
   hardware when the data is in bit-serial form using "xor" gates
   and an n-bit shift register; in this case a 32-bit shift register.
   Given a bit sequence that has been changed it is sufficient to
   change no more than 32 bits elsewhere to compensate and get the
   shift register back into the state it would have had without
   the pair of corresponding changes. Given a disk image where
   there is likely to be a fair amount of "slack space" finding
   a location to form the "compensating" change is not difficult.
   Given that no more than 32 bits need to be changed, that the
   computations are fairly simple, and that the "slack space" is
   likely to be fairly close to the data that is changed and you
   have a situation where it is fairly easy to patch a disc image
   protected only be CRC32.


From http://shekel.jct.ac.il/~citron/comm/comm-lec2/tsld011.htm
   The Cyclic Redundancy Check takes a block of data and computes a signature. 
   This signature is sent after the data.  The receiver computes its own signature 
   and compares it to the signature sent. If they don?t match an error has occurred. 

http://www.sipp.census.gov/sipp/sourceac/sourceac.htm -- Source and Accuracy Statement for
the 1992 Panel 7-Wave Longitudnal File

Jean Roth, jroth@nber.org, 2002-09-11