UML14 — Events, signals, stimuli, etc.

Here is my understanding of communication between instances on an
example (all quotes are from UML 1.4 draft (Feb 2001) of the spec).
An instance i1 performs a SendAction, according to the spec: "A send
action is an action that results in the (asynchronous) sending of a
signal". Then, the signal is delivered to say instance i2, and as a
consequence of the receipt, a SignalEvent is generated (according to the
spec, "A signal event represents the RECEPTION of a particular
(asynchronous) signal")
Now the problems:
1) the spec goes on further to say about the signal event that "A signal
event
instance should not be confused with the action (e.g., send action) that
generated it". The problem I have with my above understanding is that
the send action should not be the one generating the send event but
rather the reception of the signal should be the one generating it.
2)According to the spec: "A signal is a specification of an asynchronous
stimulus communicated between instances" where a stimulus is more
general "In the metamodel Stimulus is a communication, i.e. a Signal
sent to an Instance, or an invocation of an Operation". Thus, I conclude
that the things sent between instances are stimuli.
However, I'm a little confused of the relationship between events and
stimuli with the following sentence taken from the spec "Event instances
are generated as a result of some action either within the system or in
the environment surrounding the system. An event is then conveyed to one
or more targets. The means by which event instances are transported to
their destination depend on the type of action, the target,..."
Furthermore, how are stimuli and signals related in the metamodel?

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