OP-FOR: US military reference: careers, MOS, pay, history and defense

What this reference covers, and how to read it

Almost every question about the American military turns out to be a question about organisation. How large is the Army is really how many brigade combat teams can be generated, sustained and moved. What does a fighter cost is really what the fleet costs to keep mission-capable for a decade. Whether you can enlist is really whether one specific line score clears one specific job's cut. The published totals are the easiest numbers to find and the least informative ones, which is why the pages here are built around structures and processes rather than around inventories.

The sections divide the subject the way the institution actually divides it. Branch pages describe how each service is organised and what moving through it involves. The job database covers enlisted specialties one at a time: what the work is, where it trains, what it transfers to afterwards. Pay is kept separate from benefits because the two are decided by different mechanisms and change on different schedules. Technology is arranged by domain as opposed to by service, since aircraft, unmanned systems and satellites now cross service boundaries as a matter of routine. History concentrates on what settled an outcome rather than on the sequence of events.

Where a figure comes from a schedule, a regulation or a register, the page names the body that publishes it — the Defense Finance and Accounting Service for pay, the Military Entrance Processing Command for medical qualification, the services themselves for structure. Where a number is contested or a date is disputed, the page says so instead of picking the tidiest version. Nothing here is official, and nothing here replaces a recruiter, a career counsellor or the current edition of a regulation.

Who this is for, and where it stops

Three groups arrive here with different questions and the same underlying problem. People deciding whether to join need to know which choices bind and which can be revisited, and the answer is rarely the one the process advertises: the branch is chosen first and matters least, the specialty is chosen last in a single appointment and decides the training pipeline, the unit type, the clearance and most of what the experience is worth afterwards. People already serving arrive with a specific administrative question, usually about pay, a move or a deadline, and usually at the point where the deadline is close. And people reading defence coverage arrive needing the structure underneath a headline, because a story about force levels or a programme decision is unreadable without knowing who owns the decision.

The vocabulary is the first obstacle for all three, and it is not decoration. Grade, component, specialty, rating, allowance and combatant command each carry a precise meaning that changes what a sentence asserts, and several terms mean different things in different services. Captain is O-3 and a company commander in four services, and O-6 commanding a major ship in two. The glossary exists because almost every other page here assumes that vocabulary, and because the gap between official definition and common usage is frequently the most useful thing to know.

A pay figure or an open-specialty list changes on a cycle no reference page can track honestly, so neither is printed here as a current number. Where a number changes annually the page names the year and the body that publishes it. Where a standard can be set aside, the page says who decides. Where the honest answer depends on what the service needs this month, the page says that instead of inventing a firmer one.

Reference pages list the sources they rest on, so a claim can be followed back instead of taken on trust.