Use Xero tracking categories for divisional and branch reporting via API

Steps

1. Obtain an OAuth 2.0 access token with the accounting.settings scope and retrieve the Xero-Tenant-Id header value for the target organisation.
2. List existing tracking categories with GET https://api.xero.com/api.xro/2.0/TrackingCategories; note that an organisation supports a maximum of two ACTIVE tracking categories and four total (including archived) — plan category names accordingly.
3. Create a tracking category via PUT https://api.xero.com/api.xro/2.0/TrackingCategories with a JSON body containing Name and Status=ACTIVE, then create its options (e.g., division or branch names) by PUT-ing to /TrackingCategories/{TrackingCategoryID}/Options.
4. Assign tracking options to invoice, bill, or journal line items by including a Tracking array on each LineItem object when creating or updating transactions, specifying TrackingCategoryID and TrackingOptionID.
5. Pull divisional P&L by calling GET https://api.xero.com/api.xro/2.0/Reports/ProfitAndLoss with query parameters trackingCategoryID and trackingOptionID to filter the report to a specific branch.
6. Export the report payload and load it into a data warehouse; automate nightly pulls using a scheduled job that iterates over all active tracking options to build a full divisional reporting matrix.