Dacheng Lin has pointed out that the Tcl script simftest.tcl which can be run from the XSPEC command line using the command simftest does not work correctly. The call to the lrt.tcl script within simftest switched the order of the names of the model command files. This has been fixed in the 12.8.0d patch available from the usual site. This patch also adds options to simftest and lrt to specify a filename into which the simulation results are written. Note that documentation on simftest and lrt can be obtained within XSPEC by typing the command name.