15.11.8  MESH 

Bins  data  into  a  mesh of Z vs X,Y.  The Z values are added or averaged
together.  If Z does not exist you are given an error message.  APPEND  is
ignored for a MESH.
                                  example
     TD:BIN MESH X FROM 1 to 10 by 1 Y FROM 10 to 100 by 10