5.3.1.1.1. Invoice Number Generation

The invoice number is generated using the following components:

Taxpayer ID – Uniquely identifies the business. This value is obtained during terminal activation, typically from the activation response.
Terminal Position – identifies the terminal within the business site or branch.
Julian Date – represents the transaction date in a numeric format.
Transaction Count – a sequential number for uniqueness per day.

Each of these values is then converted from Base10 to Base64 for compact representation, and finally combined in this format:

Base64(TaxpayerID) - Base64(TerminalPosition) - Base64(JulianDate) - Base64(Count)

C# Example: implementation of the method that combines encoded values into the final invoice number:

internal string GenerateInvoiceNumber(InvoiceGenerationRequest invoiceGenerationRequest)

{

var julianDate = ToJulianDate(Convert.ToDateTime(invoiceGenerationRequest.transactiondate));

var combinedString = GenerateCombinedString(invoiceGenerationRequest.businessId,

invoiceGenerationRequest.terminalPosition,

julianDate, invoiceGenerationRequest.transactionCount);

return combinedString;

}

private int ToJulianDate(DateTime date)

{

date = date.Date;

int year = date.Year;

int month = date.Month;

int day = date.Day;

if (month <= 2)

{

year -= 1;

month += 12;

}

int A = year / 100;

int B = 2 - A + (A / 4);

int JD = (int)(Math.Floor(365.25 * (year + 4716))

+ Math.Floor(30.6001 * (month + 1))

+ day + B - 1524);

return JD;

}

private string GenerateCombinedString(long taxpayerId, int position, long julianDate, long transactionCount)

{

var base64TaxpayerNumber = Base10ToBase64(taxpayerId);

var base64Position = Base10ToBase64(position);

var julianDateBase64 = Base10ToBase64(julianDate);

var serialNumberBase64 = Base10ToBase64(transactionCount);

return $"{base64TaxpayerNumber}-{base64Position}-{julianDateBase64}-{serialNumberBase64}";

}

C# Example: Converting a Base10 value to Base64

public static string Base10ToBase64(long number)

{

if (number == 0)

{

return "A"; // 'A' represents 0 in standard Base64

}

const string base64Chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

StringBuilder result = new StringBuilder();

while (number > 0)

{

int remainder = (int)(number % 64);

result.Insert(0, base64Chars[remainder]);

number /= 64;

}

return result.ToString();

}