MRC/CCP4 file format for images and volumes

MRC2014

We have agreed an update to the MRC/CCP4 format. Details of the changes have been published in Cheng et al. (2015) "MRC2014: Extensions to the MRC format header for electron cryo-microscopy and tomography" J. Struct. Biol. 192, 146-150. See separate page for detailed format specification.

MRC2000

The original MRC/CCP4 format was agreed between the crystallography and EM communities in 1982. An update to this format was agreed in 2000 to include a machine stamp in the file header, to aid file portability. Details of MRC2000 are kept for historical reasons, but please refer to the MRC2014 page for up-to-date information.

Future updates to the format

CCP-EM have undertaken to curate the MRC format on behalf of the EM community. The format is closely linked to the MRC software library, which is distributed by CCP-EM since January 2015 (see Downloads page), and to a new lightweight Python library for MRC2014 files created by the CCP-EM team.

As part of the curation, we will look into possible future updates to the MRC/CCP4 format. The procedure will be:

• Private concerns or suggestions for the format may be emailed to Martyn Winn.
• Public discussions can take place on the CCP-EM mailing list.
• Minor updates will be considered via lightweight discussion, and advertised on this updates page.
• If the CCP-EM management committee consider that a serious issue/proposal has been raised, or if there has been an accumulation of small issues, we will convene a Change Committee to consider an update to the format. The committee will consist of representatives from at least 6 different institutions. It will be by invite only, but we welcome suggestions for membership.
• If agreement can be reached, a draft format update will be advertised on the CCP-EM website, and interested parties invited to comment. We do not expect to achieve universal agreement, but will take note of any further issues raised.
• Unless any major obstacles occur, the draft will be accepted 6 months after originally posted.