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Currently in my comp., there are some changes going on regarding project documentation. There is a LOT of time and effort spent on discussing functional specs vs. requirements doc. However, I don't think anyone here understands the reason why you would use one over the other. Therefore, I don't understand the difference myself.

Can someone shed some light on this matter please? If you have links to articles, blog posts, etc. That would be helpful too.

JAL
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Skadoosh
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4 Answers4

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A Requirements document should specify the requirements from the perspective of the end user.

User requirements document - Wikipedia

A Functional spec is a level lower and starts to define how different parts of the system should function at the System Engineering level:

Functional specification - Wikipedia

Justin Niessner
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  • In the domain of medical devices the user has needs, ie "user needs". These need to be validated to form part of the product requirements and live in the top level product requirement specification. There is not such thing as "user requirements" ... other disciplines may operate differently. – smashtastic Aug 03 '15 at 20:12
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Requirements : “what” the application should do [from user's perspective view]

Functional specification: “how” the application function

Technical specification: “how” the function implemented

Mohamed Magdy
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Requirement:

You must be in Edinburgh by 2pm tomorrow.

Specification:

Travel by car to the airport ... then take a connecting flight to .... then take the tram to the city centre ... then walk to ....

In general it's 'What's the outcome?' versus 'How are we going to do it?'.

Martin
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  • I disagree, at least based on the two wikipedia links posted by Justin (which of course may not be accurate). Under functional specification it says, "it does not include the specification of how the system function will be implemented. Instead, it focuses on what various outside agents (people using the program, computer peripherals, or other computers, for example) might "observe" when interacting with the system." – JakeStrang Sep 09 '17 at 18:17
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Business Requirement:

Implement a computerized system that calculating employees wages with required deductions and additions and pay the amount the employee is actually owed.

Functional Requirements

  • How many employees in the company and their details
  • Are they part-time, or full-time or hourly
  • What is the pay date
  • What is the deductions like TAX, PF, Community Contributions etc
Rahamath
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