User Requirements Specification. (URS).

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The User Requirements Specification (URS) is the primary document which defines what the system or equipment is to do. The URS is normally documented by the purchaser, e.g. where a manufacturing organization is purchasing a new software upgrade or a new item or test equipment with software controls, then the technical software staff within the manufacturer will normally be responsible for defining their requirements via the “user requirements specification”.

Why create a User Requirements Specification?

The need for determining and defining a URS will often arise from both Business and Regulatory and needs.

User Requirements Specification.

At what stage should the URS be drafted and approved?

The user requirements specification is the first and arguably the most important document in a software development life cycle. The content, relevancy and outputs from all other stages depend on the URS. Therefore, it is critical that time and efforts are expended, on understanding, clearly defining and documenting the contents of the URS. The development of the URS must be a collaborative effort, with active input from all impacted stakeholders.

URS content development.

Identify all interested and potentially impacted customers. If a new software system is to be developed, then who will be impacted? Who will be the key customers? The first task is to ensure that the requirements of the customer are understood and clearly documented into the draft URS.

There should be no ambiguity as regards customer expectations. The needs of the customers, must be clearly defined. Note, the requirements must be realistic and achievable. As part of the URS approval process, the demands detailed within the URS will be reviewed and may be changed to align with the practical status of timelines and resources. In such a situation, the reason for change will be communicated with the customer and further review may be necessary.

It must be possible to measure the final performance of the software, versus the URS requirements.

The URS will often divide requirements into essential requirements (musts) and if possible, a prioritized set of desirable requirements (wants). Unless the essential requirements will be met, then the software developer should not consider progressing with the software development. The desirable requirements will have a level of uncertainty attached and will need open honest communication prior to and throughout the development process.

The URS, will reference some or all of the following, depending in the specific situation; operational and functional requirements, technical and interface requirements, data and access security, resource and operational constraints, compliance needs, maintenance expectations. Specific aspects such as the functional requirements may be further defined in a subsequent “functional requirements” documents with the exception of relatively lower level software revisions.

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