‘The component parts core of <something>’ is a useful undocumented phrase defined and used in the Standard Rules to mean ‘whatever thing <something> is ultimately a part of, even if through more than one level of incorporation’.
In this instance, for example, the left lieutenant bar might be a part of the lieutenant bars which are a part of the military uniform, in which case the component parts core of the left lieutenant bar is the military uniform.
More information here (scroll toward the bottom of the post to find it).