+# to have a class of either DEBIAN + (STABLE or STRETCH64 or STABLE_BOOTSTRAP),
+# or UBUNTU + XENIAL64.
+#
+# Other notable classes:
+#
+# REPARTITION: we try to reuse partitions/filesystems to install a new
+# os into a multi-os system, if we see some basic hueristics, like the
+# right amount of them. This overrides that.
+#
+# PARTITION_PROMPT: If we don't see partitions to reuuse, prompt
+# to make sure we really want to repartition and use a completely
+# fresh install. I use this in case our repartition check has
+# a bug in it, or I accidentally set REPARTITION.
+#
+# ROTATIONAL: in a system with ssd and hdd, install to the hdd
+# instead of the default ssd.
+#
+# RAID0: Use raid 0 even if there are >= 4 disks with boot partititions.