[ccp4bb]: pseudo-merohedral twinning

[TIMM_DAVID@Lilly.com]

Hello,  Are there any suggestions for refining structures using pseudo-merohedral twinned data?  I have crystals in P21 with a=c, beta=95.63 deg, 2-fold NCS, Rmerge = 0.07.  Refinement at 2.4 Ang hangs with R-factors ~0.3 using data indexed h,k,l or reindexed l,-k,h.  Can index with similar Rmerge in C-centered monoclinic and orthorhombic space groups, but does not pack or refine.  Cheers,  Dave Timm