#5962: clarify sys.exit() vs. threads.
diff --git a/Doc/library/sys.rst b/Doc/library/sys.rst
index 7b44c86..6540311 100644
--- a/Doc/library/sys.rst
+++ b/Doc/library/sys.rst
@@ -180,19 +180,25 @@
Exit from Python. This is implemented by raising the :exc:`SystemExit`
exception, so cleanup actions specified by finally clauses of :keyword:`try`
- statements are honored, and it is possible to intercept the exit attempt at an
- outer level. The optional argument *arg* can be an integer giving the exit
- status (defaulting to zero), or another type of object. If it is an integer,
- zero is considered "successful termination" and any nonzero value is considered
- "abnormal termination" by shells and the like. Most systems require it to be in
- the range 0-127, and produce undefined results otherwise. Some systems have a
- convention for assigning specific meanings to specific exit codes, but these are
- generally underdeveloped; Unix programs generally use 2 for command line syntax
- errors and 1 for all other kind of errors. If another type of object is passed,
- ``None`` is equivalent to passing zero, and any other object is printed to
- ``sys.stderr`` and results in an exit code of 1. In particular,
- ``sys.exit("some error message")`` is a quick way to exit a program when an
- error occurs.
+ statements are honored, and it is possible to intercept the exit attempt at
+ an outer level.
+
+ The optional argument *arg* can be an integer giving the exit status
+ (defaulting to zero), or another type of object. If it is an integer, zero
+ is considered "successful termination" and any nonzero value is considered
+ "abnormal termination" by shells and the like. Most systems require it to be
+ in the range 0-127, and produce undefined results otherwise. Some systems
+ have a convention for assigning specific meanings to specific exit codes, but
+ these are generally underdeveloped; Unix programs generally use 2 for command
+ line syntax errors and 1 for all other kind of errors. If another type of
+ object is passed, ``None`` is equivalent to passing zero, and any other
+ object is printed to :data:`stderr` and results in an exit code of 1. In
+ particular, ``sys.exit("some error message")`` is a quick way to exit a
+ program when an error occurs.
+
+ Since :func:`exit` ultimately "only" raises an exception, it will only exit
+ the process when called from the main thread, and the exception is not
+ intercepted.
.. data:: flags