Hi All, A user question about the xia2 behaviour has opened a pot of worms, and I thought I would ask the community for opinions. If (for example) you are using an automated data processing or analysis tool, and the systematic absences suggest a spacegroup choice, what would you like to do:
(1) nothing - just mention this in the output (2) assign the "base" version of this spacegroup (e.g. P41212 to represent that or it's enantiomorph) (3) create multiple copies of the reflection file with all of the spacegroup options As a further question, if the spacegroup looks like P 2 21 21 (say) would you like this to be reindexed to the standard setting? Now, I suspect that there will be a wide range of opinions on this. Following #1 will give possibly strange effects if truncate tries to inflate systematically absent reflections Following #2 will result in reflections being removed by truncate #3 gives lots of reflection files and lots of mess Currently I follow #2 with reindexing to the standard setting. There have been discussions in the past of being able to flag "or enantiomorph" in the spacegroup definition in the mtz file. This would be useful here, but would not really help with the reindex or no question... Thanks! Graeme
