Originally Posted by
GalleyTeapot
Secondary duties, anything that enhances service life for others or the local community. Basically anything other than your primary work, treasurer, committee member, secretary etc of a club, etc etc.
That helps you stand out from the crowd and show that you have the breadth and capacity to take responsibility.
That said, if you do these before you join then it will broaden your CV and appeal to OASC.