Dear Phil,
One reason has been simplicity - many ARP/wARP modules operate with
space group number only. For space group 18 this would mean P21212.
Using space group name might be less robust - I remember some
compatibility problems when CCP4 introduced spaces into space group
names, this broke some of the parsers, including simple-minded ones from
ARP/wARP.
If there is, however, a strong wish for ARP/wARP to support
'unconventionally' indexed space groups - then we will certainly try to
introduce it.
With best regards,
Victor
PhilEvans wrote:
Is there a reason why Arp/warp doesn't like space group P 21 2 21?
Phil