Hi Sacha, ( appreciate the off-list info ) thanks for the correction - that makes sense. let me try a simpler question : do the TLS results need to be transformed or scaled somehow so they are on the same basis as the ones from refmac/tlsanl/anisoanl (i know this is partially a ccp4 question)? AFAIK the L and non-interecting S axes are scaled relative to the mean-squared amplitudes. i.e. i cannot explain why i can see e.g. a clear libration or non-intersecting screws from the other programs, but not from phenix. maybe consider this tlsanl output from (practically) the same input: phenix : TLS RANGE 'A 245.' 'A 252.' ALL ORIGIN 14.019 -10.476 -35.068 T 0.2961 0.2533 0.2969 -0.0097 0.0111 0.0205 L 0.0006 0.0005 0.0006 0.0006 -0.0002 -0.0001 S 0.0058 -0.0026 -0.0027 0.0035 -0.0017 0.0011 -0.0052 0.0027 TLS CENTRE OF REACTION WRT ORTHOGONAL AXES (A) : -606.636-734.593 -54.324 refmac : TLS RANGE 'A 245.' 'A 252.' ALL ORIGIN 14.019 -10.476 -35.068 T 0.4974 0.0372 0.3453 0.0674 0.2984 0.0431 L 21.5463 29.5753 20.7545 39.3304 9.2958-11.5975 S 0.6432 1.0787 -0.1449 1.2672 2.1065 1.5489 -1.1854 -0.0349 TLS CENTRE OF REACTION WRT ORTHOGONAL AXES (A) : 13.571 -13.884 -36.275 -bryan p.s: new subscription address : slow to appear on bulletin board...?