> ## Documentation Index > Fetch the complete documentation index at: https://docs.assetinfinity.ai/llms.txt > Use this file to discover all available pages before exploring further. # Organisation structure > Companies, business units, cost centres, departments and projects — the shape of the business a site hangs off, separate from where things physically are. Where a site hangs from, and where maintenance cost gets booked. Separate from the [location tree](/sites/detail) — that's geography; this is the business underneath it. ## Companies and business units | Level | What it is | | - | - | | **Company** | A legal entity. Carries its own default [currency](/config/currency) | | **Business unit** | A division within a company | Shown as one tree, because a business unit always belongs to a company. **Company** and **Business unit** are two separate buttons rather than one menu, since there are only ever the two. A business unit can't be added until at least one company exists — the button says so rather than just not offering it. ## Cost centres and departments | Level | What it is | | - | - | | **Cost centre** | Where maintenance cost is booked | | **Department** | Who owns the equipment operationally | Each shows how much depends on it — departments under a cost centre, staff and assets under a department — so deactivating one says what it would take with it. ## Projects What work and spend is grouped under when a cost centre is too coarse — a shutdown, a plant expansion, a customer job. A project carries a status, a start and end date, a budget, and whether it's billable. A [booking](/property/bookings) can be charged to a project, and capital spend accumulates against one until it's capitalised — see [depreciation](/finance/depreciation). ## Where this gets used A single-plant operation can leave most of this alone. A group running several legal entities in different currencies needs it, because that's what makes cost roll up correctly. The [sites register](/sites/register) links here directly, because the moment you need a business unit is the moment you're filling in a site that has none. The other configuration a site links out to — the vocabulary its location tree is built from.