ICS 121: Feature Specifications

A feature specification is a written description of a feature of a system.
A feature of a system is user-visible aspect of the system that provides the user some benefit. Major features might appear in the marketing material for the product. Smaller features should also be described in detail in the SRS.
Examples of features in MS Word:
- Spell checker
- Grammar checker
- Wizard to help make a document fit in fewer pages
- Widow and orphan protection: no paragraph has only a single line of text continued on the next page
A feature specification describes all the ways that the feature can be used: it is not just one example. To describe all possible uses, it should specify concepts and rules.
There is an example feature specification in this feature specification template.

Start with a feature specification template.
First, have a firm understanding of the feature in mind.
Second, give a descriptive name to the feature.
Third, write a brief English description of the feature.
Then, add "precise details" that state rules more formally. Rules can be specified using mathematical notation, regular expressions, tables, diagrams, decision trees, small mockups, or whatever is appropriate to that feature.
As you go, add notes to yourself and questions to come back to.
Afterwards, fill in pragmatic information about the feature and how it fits into your development plans:
- Priority
- Estimated effort and risk
- Feature areas are categories of features
- Links to use cases that require this feature

"Feature set" documents help you plan the overall set of features in a product
They are like a table of contents for the individual feature specifications
Rather than just making a list, you can organize the features in the feature set document so that missing or duplicate features are clear.
ReadySET feature set template