LOCI is the point(s) needed to place the object to be plotted.

          TEXT            x;y
          POLYGON         x1;y1/x2;y2/x3;y3/.../xN;yN
          REGPOLY         x;y
          ARC             x;y
          CURVE           x1;y1/x2;y2/x3;y3/.../xN;yN
          LINE            x1;y1/x2;y2/x3;y3/.../xN;yN
          ARROW           x;y
          COLDFRONT       x1;y1/x2;y2/x3;y3/.../xN;yN
          WARMFRONT       x1;y1/x2;y2/x3;y3/.../xN;yN
          OCCLFRONT       x1;y1/x2;y2/x3;y3/.../xN;yN
          STATFRONT       x1;y1/x2;y2/x3;y3/.../xN;yN
          WEATHER         x;y
          CLOUD           x;y
          SKY             x;y
          TURB            x;y
          ICNG            x;y
          SPCL            x;y
          MARKER          x;y
          PRESTEND        x;y
          PASTWTHR        x;y

     If LOCI is preceded by a '#' then the x and y values should be
     latitudes and longitudes. If the first character is a '@' then
     all points will be grid point columns and rows.  In GDPLOT3, 
     the grid coordinates are not implemented for annotation.