I'm addressing this question to the authors of BIRD 123.2, Walter, Mike, and Todd. As I understand this BIRD, the model developer has two choices for how to model jitter: 1) inside the DLL or 2) outside the DLL using the BIRD 123.2 parameters. What factors might influence a model developer to choose option 1 over 2? Can someone give me an example? Greg Edlund Senior Engineer Signal Integrity and System Timing IBM Systems & Technology Group 3605 Hwy. 52 N Bldg 050-3 Rochester, MN 55901