In the 25th CIDOC SIG meeting and the 18th FRBR-CIDOC CRM Harmonization meeting, the CRM-SIG changed the text in page xvi about disjointness as follows:
Classes are disjoint if they share no common instances in any possible world. That implies that it is not possible to instantiate an item using a combination of classes that are mutually disjoint or with subclasses of them (see "multiple instantiation" in section "Terminology").
There is no text in multiple instantiation
This issue is the same with the issue 202. The text about multiple instantiation which has been accepted by CRM-SIG is the following:
"Multiple Instantiation is the term that describes the case that an instance of class A is also regarded as an instance of one or more other classes B1...n at the same time. When multiple instantiation is used, it has the effect that the properties of all these classes become available to describe this instance. For instance, some particular cases of destruction may also be activities(e.g.,Herostratos deed), but not all destructions are activities (e.g., destruction of Herculaneum). In comparison, multiple inheritance describes the case that all instances of a class A are implicitly instances of all superclasses of A, by virtue of the definition of the class A, whereas the combination of classes used for multiple instantiation is a characteristic of particular instances only. It is important to note that multiple instantiation is not allowed using combinations of disjoint classes."
29th CRM-SIG meeting, Heraklion, October 2013