PED pedigree.dat  +SEX
   DAT xldata.dat
     fixeff 2
     animal
     xlink 
     record
   end
   ANAL UNI
   MODEL
    RAN animal NRM
    RAN xlink SEX
    FIX fixeff 
    TR record
   END
   VAR animal 1
   16
   VAR xlink 1
   4
   VAR error 1
   20