The HELP pulldown says:
Selling kits may be defined as bills of material.  A selling kit allows you to specify a kit of items with one ordering number and one price.  The kit item number itself is never manufactured or stocked.  When the invoice is created, inventory is relieved for each of the kit components.
 
Does this mean that I can have a type K as a parent part?   If I try this it says the part must be  a F, L,A,...
 
Thanks,
Laura