---
title: "Short note: Data dictionary stability"
subject: "Object Oriented Analysis and Design"
chapter: 2
key: "semester_6/object_oriented_analysis_and_design:short-note-data-dictionary-stability"
source: https://www.bctengineer.com/q/semester_6/object_oriented_analysis_and_design/short-note-data-dictionary-stability
site: BCT Engineering
---

# Short note: Data dictionary stability

Object Oriented Analysis and Design · Chapter 2: Object Oriented Analysis

- Asked in: 2073 Bhadra, 4 marks
- Answer checked by Claude Sonnet 5.5 on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_6/object_oriented_analysis_and_design/short-note-data-dictionary-stability
- Whole chapter: https://www.bctengineer.com/md/semester_6/object_oriented_analysis_and_design/chapter-2

## Question

Write a short note on Data dictionary stability.

## Short answer

A data dictionary is a central repository defining data items (names, types, meanings) used across diagrams. Domain concepts like Customer and Account are stable, so a data dictionary built on them ensures consistency; changes are controlled and traced, reducing ambiguity and easing maintenance.

## Answer

(Interpreted as the role of the **data dictionary** in OOAD and the **stability** of its contents.)

A **data dictionary** is a central repository that defines every data item used in the system: name, meaning, data type, size, allowed values, and the classes or processes that use it. In OOA it is the glossary of the domain model, listing each conceptual class, attribute and association with its definition.

**Stability** means the definitions in the dictionary stay consistent and change only in a controlled way.
- Domain concepts and their data (Customer, Account, Order) are comparatively **stable**, while functions and screens change often. Therefore an object model built on the data is more stable than a function-based model.
- Once an item is defined, every diagram and module must use the same name and meaning (consistency), so changes are made once in the dictionary and traced to every user of that item (change control and impact analysis).
- A stable dictionary avoids duplication, ambiguity and mismatch between analysts, designers and programmers.

Example entry:

| Item | Type | Meaning |
|---|---|---|
| accountNo | String(10) | Unique number identifying an account; never changes |
| balance | Money | Current amount; must be >= minimum balance |

A well maintained, stable data dictionary gives a common vocabulary and makes the system easier to maintain and extend.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. What is a data dictionary?
   A. A list of all source code files
   B. A user manual for the system
   C. A central repository defining each data item: name, meaning, type, size, allowed values and users
   D. A diagram of class inheritance
   Answer: C. It is the central glossary defining every data item used in the system. (Key point: Data dictionary definition)

2. Why is an object model built on data more stable than a function-based model?
   A. Domain concepts and their data change less often than functions and screens
   B. Functions never change
   C. Data is stored in a database
   D. Objects have no behaviour
   Answer: A. Domain data like Customer or Account is comparatively stable, while functions change often. (Key point: Why data is stable)

3. What does stability of the dictionary require when an item changes?
   A. Each diagram is edited separately
   B. The change is made once in the dictionary and traced to all its users
   C. The old definition is kept in parallel
   D. Designers may rename it freely
   Answer: B. Consistency and change control mean one change, traced by impact analysis to every user. (Key point: Controlled change)

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