Below is a description of a free protocol which enables peer-to-peer
invoicing at zero transaction cost. The sender can send invoices at
zero cost and the receiver can read the invoice data into their
systems automatically.

I'd like to hear your comments!

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THE SIMPLE INVOICING PROTOCOL - REQUEST FOR COMMENTS
19.04.2009

AUTHOR
  Juhani Jaakola
  e-mail juhani.jaak...@kolumbus.fi
  tel +358-40-5015182

1. INTRODUCTION

  The design goals of the Simple Invoicing Protocol (SINV) are:

  - Simplicity and ease of implementation and use
  - Unambiguous protocol
  - The receiver can read all essential information automatically into
    their systems
  - Peer-to-peer protocol, no hubs or exchanges needed
  - SPAM protection
  - Invoices can even be sent by typing them manually

  Invoices are sent as e-mail messages. Both the receiver and sender
must
  have an e-mail address. The receiving mailbox must be dedicated to
handle
  only SINV messages.

2. BASIC PRINCIPLE

  First the invoice sender must send a PARTNER message which contains
basic
  information of the sender. The receiver must check the information
manually
  and create an account for the sender - either manually or
  (semi)automatically. The receiver must reply to the sender when the
account
  was created or if the registration is rejected.

  Registered senders can then send INVOICE messages. The receiver MUST
reply
  to an INVOICE message whether it was successfully parsed and invoice
  processing in the receiving organization has been started. The
receiver
  SHOULD inform the sender when the invoice is paid or if there are
problems.

3. MODIFICATIONS NEEDED FOR EXISTING SYSTEMS

  The sender must modify the invoicing system to send PARTNER and
INVOICE
  messages via e-mail.

  The receiver must dedicate a mailbox for incoming invoices. The
receiver
  needs a program which can read the mailbox (via POP3 or IMAP for
example)
  and parse the PARTNER and INVOICE messages. For each PARTNER message
a
  work flow for a new account must be started. For each INVOICE
message
  a work flow for approving a purchase invoice must be started.

4. MESSAGE SYNTAX

  A message contains elements. An element contains a tag which begins
with a
  period, such as .INVOICE. All tags are in UPPER CASE.

  An element may contain a value. The value might be only one line, in
which
  case in can be typed after the tag, separated by white space. If the
  value contains many lines, the lines can be typed after the tag. The
value
  MUST NOT contain a line which begins with a dot.

  All dates are represented as YYYYMMDD. All numbers are represented
as
  digits with a leading sign, digits, decimal point (dot) and
  digits. The sign and decimal part (the dot and digits) are optional.

5. PARTNER MESSAGE

5.1. TAGS

  .PARTNER version
  Starts a partner message and indicates the version of the protocol.

  .ID email
  Identifies a partner. Partners are identified by unique e-mail
addresses.

  .BUSINESSCODE
  Identifier of the company given by local authorities. In Finland
this is
  the Y-tunnus.

  .NAME
  Name of the company.

  .ADDRESS
  Address of the company. Usually multiple lines. Format according to
  receiver's country.

  .EMAIL
  Contact e-mail if diferent from ID.

  .PHONE
  Contact phone.

  .IBAN
  Bank account in IBAN format.

  .ADRESSEE person
  Name of the person who should approve the partner account.

  .ENDPARTNER
  Ends a PARTNER message.

5.2. EXAMPLE

  .PARTNER 0.1
  .ID juhani.jaak...@kolumbus.fi
  .BUSINESSCODE FI13727719
  .NAME Dot Com Consulting
  .ADDRESS
  Solvikinkatu 11 B 28
  00990 Helsinki
  Finland
  .EMAIL juhani.jaak...@kolumbus.fi
  .PHONE +358-40-5015182
  .IBAN FI991234567890
  .ADRESSEE Helena Takalo
  .ENDPARTNER

6. INVOICE MESSAGE

6.1. INVOICE HEADER

  .INVOICE version
  Starts the INVOICE message and indicates the version of the
protocol.

  .ID number
  Unique identifier of the invoice - the invoice number.

  .PAYMENTCODE 1234567890
  OPTIONAL code that is returned via bank when this invoice is paid.
  Viitenumero in Finland.

  .SENDER email
  Identifies the sending PARTNER.

  .RECEIVER email
  Identified the receiving PARTNER.

  .DATE yyyymmdd
  Date of the invoice.

  .DUEDATE yyyymmdd
  Due date.

  .CURRENCY ccc
  Three-character currency code.

  .ADRESSEE person
  Name of the person who should check or approve the invoice.

  .CUSTOMERREFERENCE text
  Customer's project number or any accounting information

  .TEXT
  Free text.

  .ENDINVOICE
  Ends the INVOICE message.

6.2. INVOICE ROW

  .ROW
  Starts a new row in the invoice. All amounts are in ROWs.

  .DESCRIPTION text
  One-line description of the item in this row.

  .COUNT ddd.dd
  OPTIONAL how many items in this row?

  .UNIT ccc
  OPTIONAL unit for .COUNT.

  .AMOUNT ddd.dd
  Amount without VAT.

  .DISCOUNT ddd.dd
  OPTIONAL Discount amount.

  .VATPERCENT ddd.dd
  VAT percent.

  .VAT ddd.dd
  VAT amount.

  .TOTAL ddd.dd
  Total to be paid for this row.

  .TEXT
  Free text.

  .ENDROW
  Ends a ROW.

6.3. EXAMPLE

  .INVOICE 0.1
  .ID 123
  .PAYMENTCODE 1234567890
  .SENDER juhani.jaak...@kolumbus.fi
  .RECEIVER invoi...@theotherfirm.com
  .DATE 20090419
  .DUEDATE 20090503
  .CURRENCY EUR
  .ADRESSEE Helena Takalo
  .CUSTOMERREFERENCE XYZ123
  .ROW
  .DESCRIPTION Invoicing seminar after Easter
  .COUNT 1
  .AMOUNT 500.00
  .DISCOUNT 0.00
  .VATPERCENT 22.00
  .VAT 11.00
  .TOTAL 511.00
  .ENDROW
  .ROW
  .DESCRIPTION Train ticket a 33.60
  .COUNT 2
  .AMOUNT 67.20
  .DISCOUNT 0.00
  .VATPERCENT 22.00
  .VAT 14.78
  .TOTAL 81.98
  .ENDROW
  .ENDINVOICE

  The total amount to be paid is 592.98, and it has to be paid on 3rd
of May,
  2009 to the account that belongs for "juhani.jaak...@kolumbus.fi".
The
  actual account number was given by a preceding PARTNER message.
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