For static link, we must be carefule about how to
enable the block data initialization.
1) If a file contains only block data and dose
   not include any executable, it must be
   included in the file which includes the main
   program.  
   jamdat.f is a such one (and only one).
  
   In cosmos applications, it is included via 
   Zcmain.h which includes ZcosmosBD.h which
   includes jamdat.f in Cosmos/cosmos.

2) Main program must list block data names as
   external.
   The list is made and  given in jambextrn.inc
3) If a file contains block data as well as 
   some executable programs, and 
   3-a) if the executable  programs are called via
   main or its slaves, 2) is enough for enableing
    the block data  initialization.
   3-b) if the executable programs are not called
   via main or its laves, 2) cannot establish
   the block data initialization. (But this is ok 
   that the data is assumed  not used in the
   entire  program.)
4) mydummy.f,  if included and called from main,
   is to see if the block data really works.
5) vnibook.f  is a histogramming subroutine.
   It is used by some programs over  jam layer
   so we don't need it in the Cosmos library.
6) If it is  to be included, the block common should be
   enabled. --> change jambextrn.inc
   Even with that change, it will not be enabled
   until some call to vnibook routines are used.
   (see 3)

