Set the *high*- and *low*-water limits for write flow control.
- These two values control when call the protocol's
+ These two values (measured in number of
+ bytes) control when the protocol's
:meth:`pause_writing` and :meth:`resume_writing` methods are called.
If specified, the low-water limit must be less than or equal to the
high-water limit. Neither *high* nor *low* can be negative.
+ :meth:`pause_writing` is called when the buffer size becomes greater
+ than or equal to the *high* value. If writing has been paused,
+ :meth:`resume_writing` is called when the buffer size becomes less
+ than or equal to the *low* value.
+
The defaults are implementation-specific. If only the
high-water limit is given, the low-water limit defaults to an
implementation-specific value less than or equal to the