Re: Reserved prefixes

Thank you, Simon.

My view is as follows:

Prefixes - or, as RCSB Protein Data Bank refers to them "namespace prefix" , provide information on the authority defining dictionary categories and attributes.  pdbx, ndb, CCP4, phenix, pdb, rcsb, ccdc are all registered. 

While they may be used for 'local' data names, without publishing an associated dictionary, I would suggest that if files are provided as a public resource, that such a dictionary should be published in smoe manner.

Regarding registration - I believe maintaining such a registration mechanism is a suitable role for COMCIFs. This way - there will be no confusion as to the ownership of the prefix. If the mechanism is moved to GitHub with registration though "issue reporting" there - I see no issues. It will still need a manual review before addition to however the data are stored.

I am happy to see that new prefixes are being registered.  A few years ago, it was suggested within RCSB Protein Data Bankk that the IHMCIF (ihm=integrative/hybrid methods) prefix should be registered. However, at the time, the registration mechanism was broken.  I would also like to see the model archive extension (ModelCIF) registered. 

Simon, you suggest a CIF-based approach for maintaining such a list of prefixes.   

If the mechanism for maintaining prefixes is being updated, I would make two suggestions:
(a) support storing a URL pointing to where an extension is published;

(b) In addition to recording the name, email, and date of the person registering the prefix, such information may be out of date. 

Perhaps separating original vs current registration information, which can then be updated. 

So - while the late John Westbrook registered pdbx in 2000, his defunct email address is not useful today.

I thank Ezra Peisach for drafting this response, and hope that it is helpful to COMCIFS.

Be safe, and be successful, Stephen

On 2026-07-21 12:45, Simon Westrip via comcifs wrote:

The page at https://www.iucr.org/cgi-bin/cifreserve.pl describes 'reserved prefixes', primarily allowing developers to create 'local' data names without necessarily publishing an associated dictionary.

As the IUCr is leaning towards 'opening up' CIF-related content development and discussion by migrating to GitHub (while still promoting/publishing/maintaining CIF content on its websites and through its publications), I have a couple of questions:

1) Do COMCIFS (and contributors) want to continue/encourage this practice?

NB  the registry seems to be active (3 registered prefixes in 2026)

2) Should this facility be migrated to the COMCIFS GitHub repository?

For example, a simple repository containing a list of 'approved' prefixes (along with associated metadata, ideally in CIF format), with ability to request additions via GitHub's issue mechanism.


Any thoughts?


Cheers

Simon


S. P. Westrip





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