Similar to Petty Officer Third Class, advancement to Petty Officer Second Class is dependent on time in service, performance evaluations by superiors, and rate (technical specialty) examinations. The advancement cycle is currently every 6 months. Only a certain number of billets (job openings for this rank) open up biannually and all petty officers third class compete. The top scorers are chosen for advancement, but only in sufficient quantities to fill the billets available.
PettyOfficers serve a dual role as both technical experts and as leaders.
The term pettyofficer is, then, only used in abstract, the general sense, when referring to a group of pettyofficers of different ratings, or when the pettyofficer's rating is unknown.
It is common practice to refer to the pettyofficer by this short hand in all but the most formal correspondence (such as printing and inscription on awards).