This is a design question for R-core and/or CRAN folks. I think I know what the answer will be, but I thought I would ask. The plot.survfit and lines.survfit functions have an "xmax" argument. The result of this is to truncate curves at the given time value, something we often want to do. The result of xmax is more pleasing than using xlim: since it truncates the data before plotting, lines do not 'run into' the right hand side of the bounding box. Plus one avoids any warning messages about data outside the limits. When using plot then lines, it would be nice if an xmax argument from the plot call was remembered for the subsequent lines() call. I added an experimental way to do this a few years ago and it seems to work, but never documented it. I recently ran into it looking at the code and should do one or the other: document or remove. What the code does is that plot.survfit sets a global "plot.survfit" option using options(), which contains this information, and lines.survfit uses that as a default if xmax is not specified. Like I said, it works as intended, but leaving things on the global options list seems untidy, especially since it will persist until the end of the session (or next plot.survfit call). On the other hand, I can't imagine any conflict with my chosen name. At one time I thought there might be other things I want to persist (the plot.survfit option is itself a list), but nothing has come up in the 5 or so years since I created this. Document or delete? Terry [[alternative HTML version deleted]]