Section 3: Specifications

A. Definition

The Texas State Comptroller’s Model Purchasing Manual for Cities and Counties Appendix B (2) defines a specification as “a concise description of a good or service an entity seeks to buy and the requirements the vendor must meet in order to be considered for the award. A specification may include requirements for testing, inspection or preparing an item for delivery, or preparing or installing it for use.”

The Model Purchasing Manual states the purpose of the specification is “to provide purchasing personnel with a clear guide of what to buy and to provide vendors with firm criteria of minimum product or service acceptability. It is the responsibility of the Department to identify the specifications. A good specification should:

  • Set the minimum acceptability of the good or service. The term minimum acceptability is key since the vendor must know the minimum standard to determine what to provide. Too high a standard could mean wasted tax dollars. Too low a standard, and the good or service may not meet the expectations of the user.

  • Promote competitive bidding. The maximum number of responsible bidders should be able to bid to the specification. Restrictive specifications decrease competition.

  • Include provisions for reasonable tests and inspections for acceptability of the good or service. The methods and timing of testing and inspection must be indicated in the specification. Tests should refer to nationally recognized practices and standards whenever possible.

  • Provide an equitable award to the lowest qualified bidder. The buyer obtains goods or services that will perform to expectations, and the vendor is able to provide the goods or services at an equitable, agreed price.”

While specifications may be prepared by the Purchasing Department, the user department or an outside entity, the final authority and control of the specification resides with Purchasing to ensure that the specification is not too restrictive and that competition is promoted. Material changes to specifications will be coordinated with the user department.


B. Types of Specifications

There are many types of specifications depending on the requirement. Specifications may also be a combination of the different types. Exhibit 2 provides a description of the types of specifications and their use.

Exhibit 2: Specification Types

Source: Texas Comptroller’s Model Purchasing Manual for Texas Cities and Counties, March 2003
Type Description/Use

Design Specification

Detailed descriptions of a good or service, including details of construction or production, dimensions, chemical composition, physical properties, materials, ingredients and all other details needed to produce an item of minimum acceptability. Design specifications are usually required for construction projects, custom-produced items and many services.

Performance Specification

Performance specifications have terms of required performance that describe the goods and/or services. They may include required power, strength of material, test methods, standards of acceptability and recommended practices.

Combination Specifications

Combination specifications contain elements of both design and performance specifications. Some features of each are included to allow a vendor some freedom in meeting the performance needs of Bexar County and to require certain necessary design characteristics. This is probably the most common type of specification.

Brand-Name Specifications

Brand-name specifications list a good or service by brand name, model and other identifying specifications to limit the bidding to a single preferred product. This type of specification discourages competition and should be avoided unless the item is the only one that will satisfy Bexar County’s requirement. It is useful for purchasing replacement parts where only the brand name item will work. It should be noted that a local government might have to explain in a court of law why another brand will not work, so this type of specification should be used judiciously.

Brand-name or Equal Specifications

Brand name or equal specifications are similar to brand-name specifications, except that equal products are acceptable in place of the named brand.

Qualified Products List Specifications

Also known as approved products list specifications, these specifications are based on a list of products, identified by manufacturers’ names and model numbers and are the only acceptable items. These are used when quality is a critical factor and testing other products would be too time consuming or expensive.

Standard Specifications

Standard specifications include a single specification for one or more goods or services ordered on a recurring basis with the same general purpose. The same specification is used each time an order is placed or bids are advertised. Examples include office supplies, paper, janitorial supplies and copier service contracts. Standardized specifications will usually be more detailed than one-time specifications.


C. Developing Specifications and Specification Sources

The first step in writing specifications should be to try to obtain an existing specification before starting to write a new one. The existing specification can provide ideas and examples that can be used to customize the specification for Bexar County purposes. The user department should contact Purchasing for assistance in obtaining existing specifications to facilitate the specification development process.

There are numerous sources for specifications. These include: other governments, professional trade associations, professional purchasing associations and user knowledge. Specification libraries that are available include:


Appendix B (1) of the Texas State Comptroller’s Model Purchasing Manual for cities and counties provides additional references and sources for specifications and standards.

The characteristics of an effective specification include:

  • Simple: Avoid unnecessary detail, but be complete enough to ensure that requirements will satisfy their intended purpose.

  • Clear: Use terminology that is understandable to the department and bidders. Use correct spelling and appropriate sentence structure to eliminate confusion. Avoid legal jargon whenever possible.

  • Accurate: Use units of measure that are compatible with industry standards. All quantities and packing requirements should be clearly identified.

  • Competitive: Identify at least two commercially available brands, makes, or models (whenever possible) that will satisfy the intended purpose. Avoid un-needed “extras” that could reduce or eliminate competition and increase costs.

  • Flexible: Avoid very inflexible specifications, which prevent the acceptance of a bid that could offer greater performance for fewer dollars. Use approximate values such as dimensions, weight, speed, etc. (whenever possible) if they will satisfy the intended purpose. If approximate dimensions are used, it should be within a 10 percent rule of thumb unless otherwise stated in the specifications.