What is the default cardinality of an association if no cardinality is specified?

In the context of defining associations in ABAP and object-oriented programming, the default cardinality of an association is indeed set to [0..1] if no specific cardinality is designated. This means that an instance of the object making the association can either be associated with zero or one instance of the target object.

This default behavior is designed to provide flexibility in modeling relationships between objects without enforcing a strict requirement that there must always be a corresponding instance of the associated class. By using [0..1], it allows for the scenario where an object can exist independently of the target object, promoting a more adaptable design where associations can optionally exist.

The other options reflect different cardinalities. For instance, [0..*] indicates that there could be zero or more associations, which is broader than what is typically assumed by default. Similarly, [1..1] implies a mandatory association, necessitating exactly one instance, which is not the default behavior. The option indicating "none" does not relate to cardinality and does not define the absence of an association contextually. Thus, the default setting remains [0..1] in the absence of specific instructions.