DITA topics are reused in different documents the same way as they are reused in one single document. The main methods of content reuse in DITA across multiple documents are referencing, key-based reuse, and conditional processing.

In-depth Explanation:

Referencing:

DITA documents can reference or link to existing DITA topics. This method allows reuse of a topic without physically copying its content. Instead, the referenced topic is pulled into the document at the reference point.

Key-Based Reuse:

DITA allows unique keys to be assigned to topics. These keys serve as identifiers that can be used to reference the topics in different documents. When a key is referenced in a document, it retrieves the content associated with that key.

Conditional Processing:

The reuse of topics can be controlled by applying conditions. Conditions are used to specify when and where a topic is included. This is especially valuable to reuse content selectively based on specific criteria.

Example:

A company is managing documentation for a product line that includes various models of smartphones. Each model shares a lot of common information, such as basic operating instructions, safety guidelines, and warranty details.

Referencing Method: Instead of copying this shared content into every model’s manual, they create separate DITA topics for common information like “Safety Guidelines” and “Warranty Information.” In each model’s manual, they reference these topics. If they need to update safety guidelines, it can be done once in the “Safety Guidelines” topic, and all manuals that reference it will reflect the changes.

Key-Based Reuse: They assign unique keys to topics, such as “safety_guidelines_v1” and “warranty_info_v2”. In the documents for each smartphone model, these keys are referenced. If it becomes necessary to update safety guidelines for a specific model, the topic with that key is updated, and all documents that reference it will automatically receive the changes.

Content Reuse with Conditions: The documentation needs to include specific instructions for water-resistant models only. A condition, such as “water_resistant,” is applied to topics related to water protection. Then, that condition is specified in the documents for water-resistant models. This ensures that the relevant content is reused only in those manuals.