Once-Only in Documentation

Sat, 14 Feb 2026 00:00:00 +0000

What is the Once-Only Principle?

The Once-Only principle states: Data or information should be captured, stored, and maintained only once – and reused at all relevant points. It avoids redundancy, minimizes sources of error, and reduces maintenance effort. Originally known from public administration and e-government, it is gaining increasing importance in technical documentation – especially in complex, agile, and scalable systems.

Why is Once-Only Important in Documentation?

In software projects, documentation often grows in an uncoordinated manner:

Several ways to model dataflows

Sat, 17 Jan 2026 00:00:00 +0000

Data Flow or Information Flow?

Data flow describes the transmission of raw, unprocessed data, regardless of its business meaning.

In contrast, information flow concerns the transmission of processed or interpreted data that provides the recipient with clear and recognizable value.

Naturally, in an IT environment, when information needs to be transferred, this occurs based on data transfer. Data flow forms the technical foundation for information flow.

The representation forms described in this article use elements of both variants, but the purpose of the information flow is the primary focus.

Data on ProBase

Once-Only in Documentation

What is the Once-Only Principle?

Why is Once-Only Important in Documentation?

Several ways to model dataflows

Data Flow or Information Flow?