You have to declare (using our) before you can localize. Example follows.

# in main file

sub main {
 # declare, then localize:
 our (
  $ItemNumber,
  %CFL, @CFD,  #Customer 
  %DFL, @DFD,  #Destination
  %IFL, @IFD,  #Item
  %MFL, @MFD,  #Master
  %SFL, @SFD,  #Description
  %UFL, @UFD   #User
 );

 local (
  $ItemNumber,
  %CFL, @CFD,  #Customer 
  %DFL, @DFD,  #Destination
  %IFL, @IFD,  #Item
  %MFL, @MFD,  #Master
  %SFL, @SFD,  #Description
  %UFL, @UFD   #User
 );

 # set some values:
 $ItemNumber = 6;

 # call other subs.  Can be in other lexical locations, but MUST
 # be in the same namespace for this 'our' to work!
 child_sub1();
}
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# in child file 1:

sub child_sub1 {
 # declare ONLY:
 our (
  $ItemNumber,
  %CFL, @CFD,  #Customer 
  %DFL, @DFD,  #Destination
  %IFL, @IFD,  #Item
  %MFL, @MFD,  #Master
  %SFL, @SFD,  #Description
  %UFL, @UFD   #User
 );

 print "Item: $ItemNumber\n";
}
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Since our has lexically-scoped effect, you would put that declaration at the inner-most necessary lexical scope, i.e. inside each of the relevant subs. But only put the local at the point where you want to "protect", i.e. "save", any current values of these variables, i.e. in your "main" sub -- probably just below the our declaration.