UMLR — Unspecified and inconsistent notation for Observations

The specification says about the notation of Observations:

An Observation may be denoted by a straight line attached to the NamedElement it references. The Observation is given a name that is shown close to the unattached end of the line.

There are a number of places, where the Observations are shown as "t=now" and "d=duration". "now" and "duration" are never explained and unnecessary. An Observation is just a name at the end of a line connected to the observed Element. It could be ambiguous, which kind of Observation is meant. However this is also the case for many other model Elements. For a modeler this is usually no problem, because she will anyway choose a name that makes it clear, what is meant ("TransmissionDuration", "Receptiontime"). And it is always possible to look up the type in the model.

The interpretation that these are Time (or Duration) Expressions makes no sense, since they just reference one Observation. In this case the specification says:

[..] it is simply represented by its single associated Observation.

Even when we interpret "t=now" as an Expression, it would not be a TimeExpression, since its result is a Boolean.

Suggestion
Replace "t=now" with "OkSendTime" and "d=duration" with "TransmissionDuration" (alternatively with "t1" and "d1"):

• Figure 8.5 (and Figure 17.5, which is the same figure). Since it doesn't show an Expression, "with TimeExpression" should get removed.
• Table 17.1 row "DurationConstraint Duration Observation"
• Table 17.1 row "TimeConstraint TimeObservation"
• Figure 17.30 (additionally it is not clear, which Element is referenced by d. It could get connected to Message "Code")