To create a complete set of TCL commands which could recreate a
tree-file from scratch:

   IDL> mds$decomp_tree, TREENAME [ , ishot ]

This creates a TCL file
    TREENAME_MODEL.TCL   if no "ishot" specified or
    TREENAME_123456.TCL  for ishot=123456

The big difference between these two files is that the MODEL file
contains a lot of "PUT" statements to initialize nodes, while
the shot-specific version does not create these "PUT"s.
This is an important distinction if you are using the TCL file as
a template for modifications to individual shot files -- you
probably don't want to overwrite data which is already there.
On the other hand, you may need to specify the "PUT" data for
newly added nodes.  Be careful!