-(F) You tried to do a read/write/send/recv operation with an offset
-pointing outside the buffer. This is difficult to imagine. The sole
-exception to this is that C<sysread()>ing past the buffer will extend
-the buffer and zero pad the new area.
+(F, W layer) You tried to do a read/write/send/recv/seek operation
+with an offset pointing outside the buffer. This is difficult to
+imagine. The sole exceptions to this are that zero padding will
+take place when going past the end of the string when either
+C<sysread()>ing a file, or when seeking past the end of a scalar opened
+for I/O (in anticipation of future reads and to imitate the behaviour
+with real files).