Toggles the status of the given nodes twice, so that each node passes through a state of being INVALID.

vovtouch: Usage Message
      Toggle the status of nodes twice following one of these
             Start                      Finish
             VALID    ->  INVALID  ->    VALID
             INVALID  ->   VALID   ->  INVALID
             FAILED   ->   VALID   ->  INVALID
      Nodes with status different from VALID, INVALID or FAILED
      are not affected.
      This has the effect of invalidating all dependent nodes.
       % vovtouch <node_descriptor> ...
       where the node descriptor is either the name of a file
       or the VovId of a node in the dependency graph.
       -help            -- This message.
       -v               -- Increase verbosity.
       % vovtouch aa
       % vovtouch 00023456  00023457


You can produce a similar effect of invalidating all dependent nodes using the command vovinvalidate.

The difference is that with vovinvalidate, the target nodes are changed to the INVALID state, while with vovtouch, the target nodes may end up back in a VALID state if it was in a VALID state to begin with.