Hi, Torsten, On page 50, line 27 - 28 of the 01-02-2009-2 version: "The use of tags for collective operations would prevent certain hardware-optimizations and is consistent with blocking collective operations. (End of rationale.)" Should it be " ... and is inconsistent with ..." ? Thanks Bin Jia Communication Protocol Development Advanced Clustering Technology Team, IBM STG Poughkeepsie, NY 12601 Tel: 845-433-6301(T/L 293-)