 Usage:  sf = sfvonbss(r,icovu,gam,di,ord,t)  
 
 Input:

  r                      matrix, restriction matrix 
                         
  icovu                  matrix 
                         
  gam                    matrix 
                         
  di                     integer, dimension of time series 
                         
  ord                    integer, order of VAR model 
                         
  t                      integer, sample size 
                         
 Output:

  sf                     matrix of standard errors 
                         
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(C) MD*TECH Method and Data Technologies, 17.8.2000
