15.67  SORT 

SORT [SYMBOL] [[N][D]{X|Y|Z|U|V|W|THETA|RADIUS|PHI}]
     [SETS=[FROM] n1 [TO] [n2]]
     [SELECT="name"]
     [POINTS=[FROM] n1 [TO] [n2]]
     [APPEND[=ON|OFF]] [NAME="name"]
     [LOG[=ON|OFF]]
Sorts the data according to the order of the fields (X,Y...) selected.  If
fields  are  omitted  then  they  are  sorted  according  to   the   order
SYMBOL,X,DX,Y,DY,Z,DZ.  Each data set is sorted independently.

                                  example
     TD:SORT X Y Z SYMBOL
Sorts  data  so  that  all  low X are first.  Within groups of identical X
values all low Y values are first, and so on.  Since DX,DY,DZ are  omitted
the actual sorting order is:  X,Y,Z,SYMBOL,DX,DY,DZ.