hi when i do back annotation of the sdf file which i obtain from rtl compiler 4.2 i try to back annotate it using $sdf_annotate (tool)system task on the mapped file genearted by rtl compiler 4.2 which i compile using ncvlog command along with tsmc18.v. now when i do this i get only the delays specified in the sdf file and not the delays specified in the tsmc18.v using specparams why is it so. more over in the sdf files even for combination io paths posedge and negedge keywords are present which i believe is causing the warnings one of which i have cut and pasted,please help in this regard. ncelab: *W,SDFNEP: Failed Attempt to annotate to non-existent path (COND (B==1) (IOPATH (posedge A) Y)) of instance test_verilog_test.UUT.g153 of module XNOR2X1 <./sdf_files/verilog_test.sdf, line 411>. regards balaji