Specifications

To tell a system designer or vendor what is needed in a geographic information system or its components, it is necessary to formally specify the user requirements that have been identified in the needs analysis process. These user requirements, or specifications, are recorded in a critical document that is used in the design and implementation phases of an organization's GIS project. They are the plan and bill of materials needed to construct the house—or system, in this case. Specifications are the means used to translate the design of the system into a working system.

Specifications are used to define needs for many different components of a geographic information system, including the following:

• Hardware and software
• Applications and interfaces with existing (legacy) systems
• Data conversion and data quality (for both map and attribute data)
• Training
• Communications and networking
• Consulting services
• Surveying, mapping, and imaging services

Just about every component of a GIS requires specifications. They are a required part of the formal procurement process of most organizations contemplating a purchase through a request-for-bids (RFB) process or a request-for-proposals (RFP) process. The RFB process defines requirements very specifically (including vendor or brand names in some cases), asking for prices of specific items, whereas the RFP process defines general needs and requests vendors to “propose” creative solutions and quote a price for them. In the RFB case, the requirements are called technical specifications, and in the RFP case, they are usually called functional specifications.

Specifications are also a part of the system design process when the application design is accomplished “in-house” or internally to the user organization. These “program specifications” or “application requirements” define the data inputs, data processing steps, and the data outputs required for each application in the system. They describe very specifically what each application will do with the data, what data items are required from the database, what data items are to be entered by the application user, and how the screen displays, hardcopy outputs, or digital products are to look.

Whether specifying needs to a vendor or an in-house developer, specifications are a formal agreement between the user and the provider so that the user gets what he or she wants and the provider knows what to do or obtain.