Hello all, I discovered today (and fixed, I hope) a rather nasty bug that I suppose has been around for a long time, if not forever. It arose when you have an loop which contains a series of inner, embedded loops, each executed conditionally. Here is a trivial example: <script> nulldata 10 loop i=1..4 -q if i%2 loop j=1..2 -q printf "inner loop 1: j = %d\n", j endloop else loop j=2..3 -q printf "inner loop 2: j = %d\n", j endloop endif endloop </script> Up till today, "inner loop 1" would get executed each time round the outer loop (and "inner loop 2" would never get executed). The reason for this is that inner "child" loops were identified by their calling order (child 0, child 1, etc.) within the outer loop, on each iteration of the outer loop. Given the conditionality in the script above, only one inner loop gets called on each iteration of the outer loop, so although both inner loops were correctly compiled and attached, only the first ("child 0") got called. The fix for this is to identify the "children" of an outer loop not simply by calling order, but by the line number in the outer loop at which they are called. That is, when a "loop" command is found within a loop, we now do this: * What line number are we on, in the outer loop? Call this "j". * Look for a child loop that is connected to line j. * Did we find one? If yes, execute it; if not, it's a bug. My apologies for this stupid logic error. I think we should be OK now, but please report any fallout you detect. Allin.