validation on override

1.service :

override=must , I can still define a using composite without defining a composite level service wire to the embedded component(composite implementation)'s serive
override=no, I can still define a using composite with defining a composite level service wire to the embedded component(composite implementation) 's service

2. reference:
override=no, I can still define in using composite the component(composite implementation) 's reference wired to a new service value