1.  Bug in Plcray3d. WDZ, WZ1 PROBLEM. - Fixed 8 May 92.
2.  Instability noted when density gradient large.
3.  Bug in For3d.f. Insert NLYR=NLYRS(L) IN DO 537 loop. - 8 OCT 92
4.  Insert IF(WDR.NE.0.0)CALL CLOSE(NOU) - 9 OCT 92
5.  Need to test WZ2 gt N*DZ. Entered in FOR3D.FOR. - 22 DEC 92