I'm at the point of revising the User's Guide on the topic of list arguments to functions, and this task gives a different perspective on what we've been discussing. Brief recap: We've discovered a nasty problem with the way we've handled list arguments to user-defined functions, up till now. We have a fix for this but it involves a backward-incompatible change. In CVS we have a boolean switch, "protect_lists", which flips between the old behavior and the fixed behavior. The question is: what should be the default value for this switch? Right now, the old behavior is the default. Now, consider presenting this in the documentation. 1) "We have discovered a serious problem with the handling of list arguments to functions. This is now fixed as of gretl 1.7.6. Unfortunately the fix involves a backward-incompatible change. For a limited period, however, you can revert to the old behavior by doing..." 2) "We have discovered a serious problem with the handling of list arguments to functions. We have a fix for this -- sort of, but it's not activated by default since it involves a backward-incompatible change. You can 'preview' the fix by doing..." Which of these sounds better? In addition, how do we present the rules governing the use of list arguments within functions? If "protect_lists" is off by default, it seems to me the primary exposition has to be of the old, broken rules, with a note added to describe the new ones. But if "protect_lists" is on, we can give pride of place to the new, correct rules, and add a note on how old functions should be modified to conform to them. I feel that these considerations argue quite strongly for making the change now (i.e. making "protect_lists" on by default in gretl 1.7.6). Your comments, please! Allin.