Lesson 3 — What it changes, and what it cannot change
The question a finance manager asks before agreeing to any of this is whether it touches the filings. It does not. VAT returns, e-invoicing files and bank files carry the ISO 4217 currency code AED — the currency's name — and never the display symbol. The swap is cosmetic, and that word is not a hedge: it is the reason the module can be switched on in a live database in the middle of a tax period.
The mental model: a code is not a symbol. The code identifies the currency to another system — a tax authority, a bank, a trading partner's software. The symbol is what a person reads on a screen or a printed page. This module changes what people read; it does not touch what machines exchange, which is why the returns taught in course 2.1 and the e-invoices taught in course 3.1 are unaffected by anything you do here.
Two columns worth keeping. Wherever an amount appears, one of two values is in play, and knowing which one ends the argument before it starts.
| Where the amount appears | Which value is used |
|---|---|
| Screens, POS receipts, the website shop, printed PDF reports | The display symbol — this is what changes |
| VAT returns, e-invoicing files, bank files | The ISO 4217 code AED — unchanged |
Only one currency record is touched. The module changes the symbol and position fields of the AED record; beyond a few internal bookkeeping keys of its own, it writes nothing at all. Every other currency in the database is left alone: a price list in USD, a supplier bill in EUR and a bank statement in GBP all display exactly as they did before. If a second currency changes appearance in the same week, something other than this module did it.
It is not a per-company setting, and this is the part people get wrong. res.currency is database-global, so the AED record is shared by every company in the database. Switching the sign on or off applies to all of them, not only to the company you happen to be working in. There is no per-company version of this toggle, and hunting for one is time spent on a setting that does not exist.
Worked example. Marina Ridge Trading LLC shares a database with a sister company that trades mainly in USD. The finance manager enables the toggle on the Sunday. On Monday the sister company's bookkeeper, who was told nothing, opens a Dirham bill and sees the new sign, while her USD documents look exactly as they did. At the end of the month both companies file as normal, because the return carries the code AED, exactly as it did the month before.
The failure mode. "I only turned it on for my own company." You turned it on for the database. That is not a defect and there is nothing to fix — but it is a message to send before you flip the switch rather than after. One line to the other finance teams saves a morning of tickets from people who think their screens have broken.