I'm confused by the description of the cardinality attribute:

In this DAM, information flows from a source to a destination. The logical flow of information may be unidirectional or bi-directional and is usually labeled to further describe the relationship. The relationship between each class in this DAM may be described as:

Does the flow of information impact cardinality? I'm not sure why it is mentioned here. It also talks about a "relationship" but I'm not sure what that "relationship" is between and how it relates to cardinality (which usually think of as the number of values a particular data element can have in a record). 

Please clarify the use of Cardinality in this DAM.