How to document private tags

Those registering a private tag for use in ICC profiles (or owners of existing tags) can now if they wish provide documentation of the tag and how it is intended to be used, for publication on the ICC web site.

Tag documentation is completely optional. Tag owners could consider providing such documentation where it may help users in creating or applying profiles.

Private tags should normally include only metadata, and not data which affects the processing of the profile or could modify the output.

The content of of tag documentation is up to the tag owner, but where possible should include:

• An introduction describing the purpose and use case of the tag.
• The permitted type or types used by the tag. If the type is one defined in the ICC specification, the type name and signature is sufficient. If the type is not in the ICC specification, a table defining the type encoding, including byte position, length, content and encoding data types, beginning with the 4-byte tag signature.
• A detailed description of the tag contents
• A description of how it is envisaged that the tag is used
• A note stating that the tag length is required to be a multiple of four bytes
• A declaration that the tag document follows the ICC/ISO IP rules

In the case of tags which are intended to be processed by a CMM, the following should additionally be provided:

• A definition of the expected data in the tag
• An algorithmic description of how the data is to be processed
• A test data set with expected outputs after processing
• An example profile that includes the tag

To request that tag documentation is published by ICC, send the documentation to the ICC Technical Secretary. The ICC Steering Committee will approve such requests, and may decline to publish such documentation if it considers that the material conflicts with ICC policies or goals in any way.

Publication of a private tag by ICC is subject to revocation if ICC’s attention is drawn to IP conflicts.

Publication of documentation for a private tag could lead to consideration by ICC for a future version of the ICC specification.

Providers of documentation of a private tag are encouraged to join ICC.

An example private tag is ‘ICCP’, registered by ICC.