A 2005 publication from J.B.Heymann, M.Chagoyen and D.M.Belnap entitled 'Common Conventions for Interchange and Archiving of Three-Dimensional Electron Microscopy Information in Structural Biology', with corrigendum, addresses the issue of conventions for exchange of cryoEM data.
A CryoEM Standards Task Force has been set up to gather information on the different cryoEM map conventions and formats with associated metadata used by different developers. A web site has been created to collect conventions of individual software packages: http://conventions.cnb.uam.es
EMDB's current map distribution format is based on CCP4 map format. See http://emdatabank.org/mapformat.html for further information; click here to download the complete EMDB map distribution format description.