docs: extend notes on open()
diff --git a/documentation/pyserial_api.rst b/documentation/pyserial_api.rst
index 92b42e5..cec0078 100644
--- a/documentation/pyserial_api.rst
+++ b/documentation/pyserial_api.rst
@@ -111,15 +111,21 @@
.. method:: open()
- Open port. The state of :attr:`rts`` and :attr:`dtr` is applied.
-
+ Open port. The state of :attr:`rts` and :attr:`dtr` is applied.
+
.. note::
-
+
Some OS and/or drivers may activate RTS and or DTR automatically,
as soon as the port is opened. There may be a glitch on RTS/DTR
when :attr:`rts`` or :attr:`dtr` are set differently from their
default value (``True`` / active).
+ .. note::
+
+ For compatibility reasons, no error is reported when applying
+ :attr:`rts` or :attr:`dtr` fails on POSIX due to EINVAL (22) or
+ ENOTTY (25).
+
.. method:: close()
Close port immediately.
@@ -283,7 +289,7 @@
Return the state of the CD line
.. attribute:: is_open
-
+
:getter: Get the state of the serial port, whether it's open.
:type: bool