CWR file structure

CWR files are meant to be used as an information transmission system and reflect this on their structure.

The information is divided in two parts: the file name contains data uniquely identifying the file, and the contents of the file contain the actual information being sent.

File name

The CWR standard gives a special importance to the file’s name, certain metadata is stored on it to allow it being used as an unique identifier for the file.

The filename follows the pattern CWyynnnnsss_rrr.Vxx where each section means the following:

  • CW: Header indicating it is a CWR file.
  • yy: Year.
  • nnnn: Sequence.
  • sss: Sender. 2 or 3 digits.
  • rrr: Receiver. 2 or 3 digits.
  • xx: Version of the CWR standard (version x.x).
On the original CWR v2.1 specification the sequence number consists of only
two digits. Was changed to four on revision 5.

Note that the filename specification is not always followed, and so by default it should be considered optional.

File structure

The file is structured as a batch process, storing a consecutive series of transactions.

All these transactions are grouped into a single Transmission, which is then divided into several Groups, one for each type of transaction.

The start and ending of both the Transmission and the Groups are marked by a header and trailer record.

So the structure of file’s interior can be defined as: [HDR, [GRH, GRT]*, TRL]

Where the tags are the CWR record header tags, meaning:

  • HDR: Transmission header
  • TRL: Transmission trailer
  • GRH: Group header
  • GRT: Group trailer

These four types of record are the Control Records of the file, used not only to separate the sections, but also to verify the data contained in them is correct.

This is done comparing the information these records contain with the information read from the section they enclose.


There is only single Transmission in the file, and it contains all the records.


Groups contain batchs of transactions.

While there are several groups on the file, there can be only one for each type of transaction, and they indicate which type of transaction they are storing.

They are numbered consecutively, starting on 1. No two Groups may have the same number, and there can’t be any gaps between their numbers.


A Transaction is a batch of records containing all the data for a single job.

For example, a Transaction may contain information for registering an Agreement, for indicating a registering conflict with a Work, or even for indicating an error on a Transaction.

A Transaction is always of a single type, which is specified by it’s header record, and will be named after it. So if a Transaction starts with an Agreement record it is an Agreement Transaction.

The possible transactions in CWR v2.1 are:

  • Acknowledgment of Transaction (ACK)
  • Agreement supporting Work Registration (AGR)
  • Existing Work which is in conflict with a Work registration (EXC)
  • New Works Registration (NWR)
  • Notification of ISWC assigned to a Work (ISW)
  • Revised Registration (REV)

In practise, a Transaction is just a relationship of Records, and it indicates which records can or should follow the header.

Going back to the previous example, an Agreement Transaction would indicate an Agreement, the Territories it applies to and the Interested Parties for each Territory.