In XML Schema design, what feature is used to eliminate duplicate definitions by allowing reusable declarations?

Introduction / Context:
Large XML vocabularies benefit from reuse and modularity. XML Schema supports this by allowing certain declarations to be defined once and referenced across different complex types or documents, keeping schemas DRY (Don’t Repeat Yourself).

Given Data / Assumptions:

• The aim is to avoid repeating the same element definitions.
• We are using XSD terms like global and local declarations.
• We want the most direct mechanism for reuse.

Concept / Approach:
In XSD, global elements (declared as children of the schema root) can be referenced by name everywhere within the schema or by imported schemas. This contrasts with local elements, which are defined within a complex type and are not globally reusable by name. Global types (simple/complex) also support reuse.

Step-by-Step Solution:

Verification / Alternative check:
Schema design guidelines recommend global reusable building blocks plus namespaces and imports for modular design.

Why Other Options Are Wrong:
Intersection/normalized tables: Relational concepts, not XSD features.
None of the above: Incorrect because global elements are the standard solution.

Common Pitfalls:
Excessive global declarations without clear namespaces can clutter reuse; pair with thoughtful namespace design.

Final Answer:
global elements.