15.36.1  Options 

     1.  ADD - Selects the value to fill by.  If ADD=Z then the Z value of
         the fill source is used in the fill.
     2.  BY=n  -  Selects  the  data set to use in filling other data set.
         You may specify the set number or the name enclosed in quotes.
     3.  LEVEL - Selects the number of passes to test.  0=no fractions.
     4.  LIMITED - Selects data by range of X,Y,Z
     5.  LINES - Selects the range of lines or rows of a mesh to fill.
     6.  LOG - Tells you how many points have been filled.
     7.  POINTS - Selects the range of points or columns to fill.
     8.  SETS  -  Selects the data sets to fill.  The fill source is never
         filled.
     9.  SELECT - Selects the data sets to fill by name.