Released versions of package FD

5.20 (1998, October): *** First release consisting of program and subroutines files 'modfd.for','fdmod.for','fd2d.for','fdaux.for','gmtra.for', 'newpar.for','newpar.pl','fdmax.pl', demo data, scripts and history files. *** 5.30 (1999, June): 'fd2d.for', 'fdaux.for': Erroneous sign in output snapshots fixed. Comments in 'fdaux.for' improved. 'fdmod.for','newpar.for': Updated according to changes in 'fdaux.for'. 'modfd.for': Updated according to changes in 'model.for'. 'fdmax.pl: Updated according to changes in 'grdnorm.for'. 'snap.cal': Confused div and rot corrected. 'fd.h': Snapshots supplemented with the receivers. 'modfdps.h': Colours of complex blocks changed. *** new *** 'addrec.cal': Script for 'grdcal.for' to overlay snapshots with receiver positions. 5.40 (2000, May): 'modfd.for': Problems with gridpoints at interfaces fixed. 'fdaux.for': Erroneous averaging along the X1 axis fixed. 5.50 (2001, June): 'fdmax.pl': Missing apostrophes at data filenames fixed. 'fdsnaps.htm': Mistype in a comment line corrected.