-/* Converts all the temporary transformations, if any, to
- permanent transformations. Further transformations will be
- permanent.
+/* Converts all the temporary transformations, if any, to permanent
+ transformations. Further transformations will be permanent.
+
+ The FILTER command is implemented as a temporary transformation, so a
+ procedure that uses this function should usually use proc_open_filtering()
+ with FILTER false, instead of plain proc_open().
+