#### 2.1.4 Configuration, specialization, and constraints

The extension facilities of DITA allow existing vocabulary and constraint modules to be combined to create specific DITA document types. Additionally, vocabulary modules can be extended to create more-specialized markup to meet new requirements not satisfied by existing markup.

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Parent Topic: Base architecture

Child Topics:

2.1.4.1 Overview of DITA extension facilities

2.1.4.2 Configuration (Document type shells)

2.1.4.3 Specialization

2.1.4.4 Constraints

Sibling Topics:

2.1.1 Introduction to DITA

2.1.2 DITA markup

2.1.3 DITA processing