An attribute name should not be used in more than one relation.

This statement is not entirely correct. In the context of relational databases, an attribute name can be used in more than one relation. What is important is that within a single relation (or table), each attribute (or column) should have a unique name to avoid confusion.

However, the same attribute name can be used in different relations. For example, you might have a "Customer" relation with an attribute named "Address", and a "Supplier" relation with an attribute also named "Address". This is perfectly acceptable and often occurs in database design.

The key is that each attribute within a relation should uniquely identify a characteristic of the entity or relationship that the relation represents.