CDWRIT(S,F,I,V,n,s,B)
[Cellular decomposition (list of cells) write.
S is a lexicographically ordered list
of sample points for some collection C of cells in 
r-dimensional Euclidean space, for some r>=1.  F is either the null 
list, or a lexicographically ordered list of 
defining formulas for C.  I is a lexicographically ordered list of 
cell indices for C.  V is a variable list of length r.  n is a 
nonnegative @beta -digit@. s is a @beta -digit@.
B is the r-variate integral polynomial basis of the cad.  
For each cell c in C, the cell index and dimension of c are written 
in the output stream. If s>0, then an exact description of the
sample point of c is written in the output stream (if it is nonNULL).
If n>0, a decimal approximation to the sample point of c is written
with n decimal digits following the decimal point of each coordinate 
(if it is nonNULL).  If F is nonNULL, the defining formula of c is 
written.  The output buffer is emptied beforehand and afterwards.]
     const NULL=0.
     safe S',F',I',S_,I_,F_.
(1)  S'=S;  F'=F;  I'=I;  BLINES(1);
     while I'~=() do {  ADV(I';I_,I');  ADV(S';S_,S');
     if F'~=() then ADV(F';F_,F') else F_=NULL;  
     CELLWL(S_,F_,I_,V,n,s,B);
     if I'~=() then { cwrite(','); emptob }  }; BLINES(1);
     return..