By the time of the First World War, their ranks had been expanded with the adoption of modern technology in the Royal Navy to include telegraphists, electricians, shipwrights, artificer engineers, etc. Both warrant officers and commissioned warrant officers messed in the warrant officers' mess rather than the wardroom (although in ships too small to have a warrant officers' mess, they did mess in the wardroom). Warrant officers and commissioned warrant officers also carried swords, were saluted by ratings, and ranked between sub-lieutenants and midshipmen. In 1949, the ranks of warrant officer and commissioned warrant officer were changed to "commissioned officer" and "senior commissioned officer", the latter ranking with but after the rank of lieutenant, and they were admitted to the wardroom, the warrant officers' messes closing down. Collectively, these officers were known as "branch officers", being retitled "special duties" officers in 1956. In 1998, the special duties list was merged with the general list of officers in the Royal Navy, all officers now having the same opportunity to reach the highest commissioned ranks. The Royal Australian Navy rank of warrant officer (WO) is the Navy's only rank appointed by warrant and is equivalent to the Army's WO1, and the RAAF's warrant officer. The most senior non-commissioned member of the Navy is the Warrant Officer of the Navy (WO-N), an appointment that is only held by one person at a time. The Australian Army has two warrant officer ranks: warrant officer class two (WO2) and warrant officer class one (WO1), the latter being senior in rank. The equivalent rank of WO2 in the Navy is now chief petty officer, and the RAAF equivalent of the Army's WO2 is now flight sergeant, although in the past there were no equivalents. All warrant officers are addressed as "sir" or "ma'am" by subordinates. To gain the attention of a particular warrant officer in a group, they can be addressed as "Warrant Officer Bloggs, sir/ma'am" or by their appointment, e.g. "ASM Bloggs, sir/ma'am". Some warrant officers hold an appointment such as company sergeant major (WO2) or regimental sergeant major (WO1). The warrant officer appointed to the position of Regimental Sergeant Major of the Army (RSM-A) is the most senior enlisted soldier in the Australian Army and differs from other Army warrant officers in that their rank is just warrant officer (WO).