## component is a junction
	n_named_ports = 0;
	
	## get labelled ports
	for [bond, bond_name] = comp
	  if (index(bond_name, "bond") == 1)
	    if (! exist("bond.label"))
	      bond.label = "[]";
	    if (! isfield (bond, "label"))
	      bond.label = "[]"
	    endif
	    if (! strcmp(bond.label, "[]"))
	      n_named_ports += 1;
	      port_label = bond.label;
	    endif
	  endif
	  eval(sprintf("comp.%s = bond;", bond_name));
	endfor
	
	## attach labels to unlabelled ports
	if (n_named_ports == 0)
	  mtt_info(sprintf("Defaulting all ports on junction %s to 'in'", \
			   comp_name), infofile);
	  for [bond, bond_name] = comp
	    if (index(bond_name, "bond") == 1)
	      bond.label = "in";
	    endif
	    eval(sprintf("comp.%s = bond;", bond_name));
	  endfor
	elseif (n_named_ports == 1)
	  mtt_info(sprintf("Defaulting all ports on junction %s to %s", \
			   comp_name, port_label), infofile);
	  for [bond, bond_name] = comp
	    if (index(bond_name, "bond") == 1)
	      bond.label = port_label;
	    endif
	    eval(sprintf("comp.%s = bond;", bond_name));
	  endfor
	elseif (n_named_ports != bond.n_bonds)
	elseif (n_named_ports != comp.n_bonds)
	  mtt_error(sprintf("Junction must have 0,1 or %i port labels", \
			    n_bonds), errorfile);
			    comp.n_bonds), errorfile);
	endif
	
      else
	## component is not a junction
	for [bond, bond_name] = comp
	  if (index(bond_name, "bond") == 1)
	    if (strcmp(bond.label, "[]"))