Final answer:
The relationship code that identifies items that can be used in place of other items only for particular uses or under certain conditions is called subtyping.
Step-by-step explanation:
The relationship code that identifies items that can be used in place of other items only for particular uses or under certain conditions is called subtyping. In computer science, subtyping is a mechanism that allows a derived class to be treated as a base class, providing flexibility and code reusability.
Subtyping is commonly used in object-oriented programming languages like Java and C++. For example, a subclass of a class can be used wherever the base class is expected. This allows for polymorphism, where different objects can be used interchangeably based on their commonality.