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Re: [ccp4bb] pointless (1.2.0) and enantiomorphic SG's
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CCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999
Previous message:
Subject: Re: pointless (1.2.0) and enantiomorphic SG's
From: Harry Powell harry {- at -} MRC-LMB {- dot -} CAM {- dot -} AC {- dot -} UK
Date: 2007-11-09		Next message:
Subject: Re: pointless (1.2.0) and enantiomorphic SG's
From: Ian Tickle I {- dot -} Tickle {- at -} ASTEX-THERAPEUTICS {- dot -} COM
Date: 2007-11-09


Subject: Re: pointless (1.2.0) and enantiomorphic SG's
From: Kevin Cowtan cowtan {- at -} YSBL {- dot -} YORK {- dot -} AC {- dot -} UK
Date: 2007-11-09

Eleanor Dodson wrote:
> Offering a selection of space groups compatible with a point group will
> not require reindexing.
> Some point groups of course permit reindexing, but one hope you have
> chosen a consistent set as you combine data sets into an MTZ file -
> pointless and the GUI both offer ways to check this.
>
> Phasing cannot be carried out till you have chosen a spacegroup, and any
> existing phase associated data should probably be weeded out as part of
> a "Assign Spacegroup" function.

Good, that makes sense.

Note however we have introduced a constraint on the data model:
- Phasing and multiple spacegroups are inconsistent.

Actually, IIUC, it's more complicated, since heavy atom location comes
before phasing, but produces phases with enantiomorph ambiguity.
Grahame's 4-step indicator of uncertainty provides the right sort of
framework. But each step is associated with a corresponding set of
restrictions on what is valid in the file - and in the case of phases,
what they actually mean.

CCP4bb navigation

CCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999
Previous message:
Subject: Re: pointless (1.2.0) and enantiomorphic SG's
From: Harry Powell harry {- at -} MRC-LMB {- dot -} CAM {- dot -} AC {- dot -} UK
Date: 2007-11-09		Next message:
Subject: Re: pointless (1.2.0) and enantiomorphic SG's
From: Ian Tickle I {- dot -} Tickle {- at -} ASTEX-THERAPEUTICS {- dot -} COM
Date: 2007-11-09
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