Staff (military)
General Staff Officer (Grade 1), informally known as G1: Ranked Lieutenant Colonel or a Colonel
General Staff Officer (Grade 2), informally known as G2: Ranked Major
General Staff Officer (Grade 3), informally known as G3: Ranked Captain

A Branch (စစ်ရေး): A Branch, called စစ်ရေး or ရေး for short in Burmese, is responsible for every aspect of personnel management such as medical and military. 
Adjutant Staff Officer (Grade 1), informally known as A1: Ranked Lieutenant Colonel or a Colonel
Adjutant Staff Officer (Grade 2), informally known as A2: Ranked Major
Adjutant Staff Officer (Grade 3), informally known as A3: Ranked Captain

Q Branch (စစ်ထောက်): Q Branch, called စစ်ထောက် or ထောက် for short in Burmese, is responsible for logistical aspects such as supply and transport as well as ordnance service.
Quartermaster Staff Officer (Grade 1), informally known as Q1: Ranked Lieutenant Colonel or a Colonel
Quartermaster Staff Officer (Grade 2), informally known as Q2: Ranked Major
Quartermaster Staff Officer (Grade 3), informally known as Q3: Ranked Captain

Prussia: Prussia adopted Austria's approach in the following years, especially when Gerhard von Scharnhorst, who as a Hanoverian staff officer had worked with the Austrian army in the Austrian Netherlands in the early 1790s, took charge. Initially, the Prussian Army assigned a limited number of technical expert officers to support field commanders. Before 1746, however, reforms had added management of intelligence and contingency planning to the staff's duties. Later, the practice was initiated of rotating officers from command to staff assignments and back to familiarize them with both aspects of military operations, a practice that, with the addition of enlisted personnel, continues to be used. After 1806, Prussia's military academies trained mid-level officers in specialist staff skills. In 1814, Prussia formally established by law a central military command—Prussian General Staff—and a separate staff for each division and corps. Despite some professional and political issues with the Prussian system, especially when viewed through the prism of the 20th century World Wars, their General Staff concept has been adopted by many large armies in existence today.

United Kingdom: Before the Crimean War staff work was looked at "with great disdain" in the British Army; the hardships of that war caused by disorganization led to a change in attitude. The General Staff in Britain was formed in 1905, and reorganized again in 1908. Unlike the Prussian staff system, the British Army was thought too small to support separate staff and command career streams. Officers would typically alternate between staff and command. Beevor, Inside the British Army, says instead that the terrible cleavages between staff and line units caused by the enormous losses during the trench warfare of the World War I meant that senior British officers consequently decided that all officers would rotate between staff and line responsibilities, preventing the development of a separate general staff corps.

United States: The National Security Act of 1947 instead created a Joint Staff populated by military service members who, rather than becoming career staff officers on the German general staff model, rotate into (and back out of) joint staff positions. Following the major revision of Title 10 of the United States Code by the Goldwater–Nichols Act in 1986, the Joint Staff of today works directly for the Chairman of the Joint Chiefs of Staff rather than the corporate Joint Chiefs of Staff, as they did from 1947 to 1986. Under this scheme, operational command and control of military forces are not the province of the Joint Staff, but that of combatant commanders, who report through the Chairman of the Joint Chiefs of Staff unless otherwise directed, to the Secretary of Defense.

Continental Staff System: The "Continental Staff System", also known as the "General Staff System" (GSS), is used by most NATO countries in structuring their militaries' staff functions. In this system, which is based on one originally employed by the French Army in the 19th century, each staff position in a headquarters or unit is assigned a letter-prefix corresponding to the formation's element and one or more numbers specifying a role.
The staff numbers are assigned according to custom, not hierarchy, traceable back to French practice; i.e., 1 is not "higher ranking" than 2. This list reflects the SHAPE structure:

1, for manpower or personnel
2, for intelligence and security
3, for operations
4, for logistics
5, for plans
6, for signals (i.e., communications or IT)
7, for military education and training (also the joint engineer)
8, for finance and contracts. Also known as resource management.
9, for Civil-Military Co-operation (CIMIC) or civil affairs.
Since the original continental staff system only covered branches 1 through 6, it is not uncommon to see 7 through 9 omitted or having various meanings. Common variation include merging of 3 and 5 to 3, Operations and Plans; omitting the training branch and utilizing 7 for engineering (as seen in US Military Sealift Command and Multinational Forces-Iraq (MNF-I)) and replacing 9 with a legal branch (making CIMIC a part of another branch, i.e. 2 or 4) as seen with the UK Permanent Joint Headquarters.
Derived from the Prussian Große Generalstab (Great General Staff), traditionally these staff functions were prefixed by the simple G, which is retained in place for modern army usage. But the increasing complexity of modern armies, not to speak of the spread of the staff concept to naval, air and other elements, has demanded the addition of new prefixes. These element prefixes are:

A, for air force headquarters;
C, for combined headquarters (multiple nations) headquarters;
F, for certain forward or deployable headquarters;
G, for army or marine general staff sections within headquarters of organizations commanded by a general officer and having a chief of staff to coordinate the actions of the general staff, such as divisions or equivalent organizations (e.g., USMC Marine Aircraft Wing and Marine Logistics Group) and separate (i.e., non-divisional) brigade level (USMC MEB) and above;
J, for joint (multiple services) headquarters, including the Joint Chiefs of Staff);
N, for navy headquarters;
S, for army or marines executive staff sections within headquarters of organizations commanded by a field grade officer (i.e., major through colonel) and having an executive officer to coordinate the actions of the executive staff (e.g., divisional brigades, regiments, groups, battalions, and squadrons; not used by all countries); S is also used in the Naval Mobile Construction Battalions (SeaBees) and in the Air Force Security Forces Squadron.
U, is used for United Nations military operations mission headquarters.
CG, is unique to the US Coast Guard's Assistant Commandants (Headquarters staff), previously using the G prefix.
On some occasions the letter E can also be observed, though it is not an official term. In that case it is for element and it will be used to identify a small independent element, that is a part of a non-staff organization; i.e., an E3 is an operational element on a logistics site or an E4 is a logistics element on a forward medical support site.
Thus, the personnel officer of a naval headquarters would be referred to as N1. In reality, in large organizations each of these staff functions will require the support of its own large staff, so N1 refers both to the office and the officer in charge of it. The continental staff system can be carried down to the next level: J1.3 (or J13, sometimes the dot-separator is omitted) is thus the operations officer of the personnel office of a joint headquarters, but the exact definition of the roles at this level may vary. Below this, numbers can be attached following a hyphen, but these are usually only positional numbers assigned arbitrarily to identify individuals (G2.3-2 could be the budget officer in the operations section of the intelligence department; A1.1-1-1 might simply be a receptionist).

Manpower or personnel: The manpower or personnel officer supervises personnel and administration systems. This department functions as the essential administrative liaison between the subordinate units and the headquarters, handling personnel actions coming from the bottom up (such as a request for an award to be given to a particular soldier) or from the top down (such as orders being received from the army level directing that a particular soldier be reassigned to a new unit outside the command). In army units, this person is often called the Adjutant. The S-1 also works with the postal mailing office, and deals with awards and ranks as well.

Intelligence, security, and information operations: The intelligence section is responsible for collecting and analyzing intelligence information about the enemy to determine what the enemy is doing or might do, to prevent the accomplishment of the enemy's mission. This office may also control maps and geographical information systems and data.