[ccp4bb] twwining operator

[siva charan]

hello
I have a data set to 2.4 A, which has space group of *P21 *.  From the 
cumulative intensity distribution graph, indicates  that  data  is  
twinned . To  run the  detwin program  in ccp4, one has to know the 
twinning operator. Can anybody help me, how can I get the twinning 
operator for monoclinic space group. I have checked for twin operators 
at http://www.ccp4.ac.uk/dist/html/twinning.html, but  there are no 
twining operators for monoclinic  space group. 

regards
siva