CAD (in ccp4) should be right program. You input an mtz file and write-out any column you choose into the output.  Best, Kianoush --- On Thu, 8/7/08, David Waterman <[log in to unmask]> wrote: From: David Waterman <[log in to unmask]> Subject: [ccp4bb] make I+ and I- columns in mtz To: [log in to unmask] Date: Thursday, August 7, 2008, 9:22 AM Hi all, I have an MTZ file with I, SIGI in which Friedel pairs are on separate lines, i.e.  LIST OF REFLECTIONS  ===================    -6  -6  -6    24173.00    898.47     6   6   6    23523.00    872.92    -7  -5  -5    60313.00   1232.77     7   5   5    58022.00   1288.21 All I want to do is make an MTZ file with columns H, K, L, I(+), SIGI(+), I(-) and SIGI(-) without doing anything else to the data. Should be easy, but I can't find the right tool to do it! Cheers David