Note on PC versions of feffit and RDF (UWXAFS binary) files:

  If you are NOT using the RDF (or UWXAFS binary) file type for your data
  analysis, the three versions of the executables 'feffit255' should
  give identical results.

  If you are using the RDF file type (and programs like IDP), then you
  should try the three different versions and use whichever one works. 
  If none work, let me know.  You'll know which one is not working
  because you'll get messages like this:

    openrf: wrong file type
    inpuwx: error opening file        my.chi
    openrf error code    3                                   

  An error message like this:
    inpuwx error: reading file      fepcmu2.chi
     no skey or nkey given to specify record,            
     or an incorrect skey or nkey given  

  means that you only gave the file, not the SKEY or NKEY.

  The basic problem here is that the RDF files have a built-in 'data size'
  that must be correct to read the data file.  In the old days, this was a 
  machine-dependent number, and there was no choice but to conform to the
  machine size.  Nowadays, there are several legitimate choices for the
  data size, but all the codes using the files have to agree.  Sadly, there
  isn't much agreement and codes with 'data size' = 128 and 512  are
  common.   Two executables use for the two different values for the RDF
  data size.  Again, one (and only one) of them should work.

--Matt