Order slips on a bill spike, with typed lines and totals on each. The top slip is pierced through. It is printed in black and a red ink.

Mantel

The comanda becomes a factura

The bill

A white-label operations platform for restaurants and bars in Ecuador, from the floor to the SRI.

Juan M. Cornejo

Mantel

A notebook

This notebook covers one part of Mantel: how a comanda becomes an electronic factura for the SRI, to the cent.

Notes2
The bill, sketched3
The comanda becomes a factura4
One comanda, to the cent5
Try it6
The facturas, in the app7
The comanda, in the kitchen8
From the table to the SRI9
In short10

A white-label operations platform for restaurants and bars in Ecuador, from the floor to the SRI. Built for one room first.

1Mantel

Notes

Three venues run on Mantel, on the same code: El Encanto, Sincopa and La Cuadrilla. The first two have their own colours.
In Ecuador a menu price includes the IVA, the 15% tax. The bill takes it back out, line by line.
A discount comes off the net base. The IVA is then charged on what is left, followed by the venue’s service charge, 10% in this example. The service carries no IVA.
The factura’s XML calls the service propina. In the app, Propina is now a different line: a tip added at payment, outside the factura.
The screen, the server and the XML each round the numbers, so all three must agree. For the screen and the server, the code gives the reason: a bill that is a cent off is one nobody can explain at the table.
The IVA is spread over the lines by largest remainder: the leftover cents go to the lines with the largest fractions, so the lines sum to the total.
The access key is 49 digits. The last one is a módulo 11 check over the other 48.
The SRI refuses a factura with a $0 total or with no tax total, so Mantel’s builder refuses them first. A $0 bill closes with no factura.
An invoice can be borrador (draft), firmada (signed), pendiente (pending), autorizada, error or anulada (voided). The SRI’s answer leaves it autorizada, pendiente or error. A job runs every ten minutes: it retries a pendiente, and a borrador or an error for 24 hours.

2Notes

The bill, sketched

Figure 1. A bill, sketched in code. The lines and their prices are at the top, the totals under a rule, and the access key at the foot.

3Mantel

Chapter 1

The comanda becomes a factura

A comanda is a table’s order. When the table closes, Mantel turns it into a factura, an electronic invoice for the SRI, Ecuador’s tax service. The figures on the screen, on the server and in the XML must match to the cent.

Menu prices include the IVA, Ecuador’s 15% tax. The bill takes the IVA back out of each line to find the net base, takes the discount off the net, then adds the IVA and the venue’s service charge, 10% in this example. The factura spreads the IVA over the lines, and its 49-digit access key ends in a check digit.

The next page works through one invented comanda. On the page after it, change the order and pick an answer from the SRI.

4The comanda becomes a factura

One comanda, to the cent

Line	Qty	Net unit	Net	Discount
Lines, with the IVA taken out
Locro de papa	2	7.39	14.78	1.48
Ceviche de palmito	1	7.83	7.83	0.78
Copa de vino tinto	2	6.09	12.17	1.22
Agua con gas	1	2.17	2.17	0.22
The bill
Subtotal, without IVA				36.95
Discount, 10% of the net				3.70
IVA, 15%				4.99
Service, 10%, no IVA				3.33
Total				41.57

18102026fecha01tipoComprobante9999999999999ruc1ambiente001001serie000000128secuencial20261018codigoNumerico1tipoEmision1digitoVerificador

The discount is shared over the lines by weight, and the IVA over the taxable lines. Each share uses largest remainder, so every column sums to its total.

Table 1. One invented comanda as a bill, with its 49-digit access key. Computed when the page was built, with Mantel’s functions ported to this page. The issuer (emisor) is the demo’s: DEMO, SIN VALIDEZ TRIBUTARIA.

5Mantel

Try it

Comanda	Price	Qty

the guest declines the servicediscount

the SRI answers (a simulation)

the XML, unsigned

DEMO · SIN VALIDEZ TRIBUTARIA

Figure 2. An invented comanda run through Mantel’s bill, XML and access key, ported to this page. Change a quantity, the discount or the service, then pick an answer from the SRI. The answers are simulated, and nothing is signed or sent.

6Try it

The facturas, in the app

Mantel’s Facturas list: counters for the facturas authorised and the total invoiced, tabs for each state, and two numbered rows, a nota de crédito and a factura, both marked AUTORIZADA.

Plate 1. The Facturas list of Mantel’s demo build, with invented data. Each factura is one numbered row with the SRI’s answer, and a correction is a second document.

7Mantel

The comanda, in the kitchen

Mantel kitchen display: a ticket for table S3, check 1, four guests, with a vegetarian restriction and two dishes, each with a LISTO button.

Plate 2. Table S3 on the kitchen display of the demo build. The check number the kitchen sees is the one the bill carries; the factura gets its own number.

8The comanda, in the kitchen

From the table to the SRI

Figure 3. How a comanda reaches the SRI, drawn as a line through stations: the bill, the XML and its key, then the SRI’s receipt (recepción) and authorisation (autorización). The SRI’s answer is authorised, pending or an error, and a pending one goes round again.

1The comanda to the bill: net base, discount, IVA, service.
2The bill to the XML and its 49-digit key, then the signature.
3The SRI receives it (recepción), then answers (autorización): authorised, pending, or an error. A pending one is tried again every ten minutes.

9Mantel

In short

A factura is sent when the table closes, but it is not always authorised then. The SRI can authorise it, leave it pending or return an error.

The rest of Mantel is in the case study: the floor, the kitchen displays, inventory and cost, roles and the public carta.

the case study

another notebook El Encanto

notebooks

10In short