[phenixbb] distance threshold for special positions?

[Alastair Fyfe]

I'd be grateful for pointers to documentation/source regarding 
phenix.refine's criterion for flagging an atom's coordinates as 
coinciding with a special position. For shelxl I noticed a distance 
cutoff of 0.02 to the symmetry equivalent position seems adequate for 
the data I'm working with.  For phenix.refine the threshold is higher 
but I haven't found documentation for the cutoff used.
thanks,
Alastair Fyfe