              Data items in the PHASING_MIR_DER_SHELL category record\
               statistics, broken down into shells of resolution, for an MIR\
               phasing experiment.\
\
               This list may contain information from a number of different\
               derivatives; _phasing_MIR_der_shell.der_id indicates to which\
               derivative a given record corresponds. (A derivative in this\
               context does not necessarily equate with a data set; see the\
               definition of the PHASING_MIR_DER category for a more\
               thorough discussion of the meaning of derivative.)