The fundamental procedure executed by vovbuild is vtk_transition_add, which is typically called indirectly by the FDL procedures T and J. The procedure takes six arguments:
  • The working directory
  • The environment
  • The resources
  • The command line
  • The list of inputs
  • The list of outputs
This procedure is controlled by make(ctrl,action), which can be one of trace, script, or echo.
  • If make(ctrl,action) is trace, this procedure is an interface to vtk_transition_add_to_trace, which takes the same arguments. The effect of this procedure is to add the specified transition to the trace. If the transition already exists, its resources will be augmented, if necessary. At least all the files specified in the input list will have arcs into the transition, and similarly for the outputs. Existing transitions with output arcs to files in the list of outputs are deleted.
  • If the action is script, the procedure prints on stdout an executable script valid for the architecture make(arch).
  • If the action is echo, the transition information including inputs and outputs is echoed on stdout.
vtk_transition_add . "BASE" "unix" "clevercopy $filein $installdir" "$filein" 
"$installdir/[file tail $filein]"


The VOV system enforces limits on the lengths of some of these parameters. Calls to vtk_transition_add with parameters exceeding the limit will fail to add the transition and generate a message.

Current limits (in characters) are:
  • Command 40960
  • Environment spec 512
  • Directory 1024
  • Resource spec 1024