It is essential that any product or service requested be clearly described so that the supplier can respond to the purchaser's request without ambiguity. This description is referred to as the "specification" i.e. "the document describing the requirements to which the product or service must conform".

The CUP Guidance No. 30 on Specification Writing, is about to be withdrawn (originally produced in 1991).  Guidance can now be found in the OGC's  Successful Delivery Toolkit and in particular the Requirements Definition & Procurement Strategy and the Expected Outputs & Outcomes sections.  It is understood that the OGC is about to produce a new briefing paper on specification writing that will appear in the new Version, V4.5, of the Successful Delivery Toolkit.

The specification provides a description of what is needed to buy and/or what the supplier is expected to tender against and, if successful, deliver. It should include performance targets or criteria for goods, services or work acceptance. The specification should also help provide tender evaluation criteria.

Specification preparation is an essential preliminary step in the purchasing cycle. Refer to Section E.3.13 - Checklist Checklist - for a summary checklist when preparing a specification.

A specification should be unambiguous so that the product or service fits the user's needs, but not so explicit that it prevents negotiation or discourages the supplier from proposing innovative solutions or offering better value for money. It must be prepared using language that suppliers will understand. If an employee does not feel they have the knowledge to create a specification then a specialist should be employed.

Writers of specifications are responsible for ensuring that what is purchased conforms to the requirements of health, safety, environmental and other relevant legislation.

References to specific model numbers or proprietary names of one supplier will restrict competition (e.g. IBM rather than IBM Compatible) and must be avoided unless there are sound reasons to the contrary (e.g. for good commercial reasons a standard product line has been agreed to).

The specification is included with the invitation to tender. It must be agreed with the winning bidder and forms the principal part of the formal contract agreed between the customer and the supplier. Once the specification is included as part of the contract or order it can be changed only by agreement with the supplier. Changes to specifications after the contract or order has been placed and accepted can incur cost and/or delay the delivery.

The end user is responsible for providing a sufficiently detailed description of the required product or service to enable specialist purchasing staff to undertake the purchasing exercise effectively. Where the user does not have the authority to procure, the requirement should be discussed with a designated procurement specialist.

Wherever appropriate, the description should include reference to relevant British or European Standards (see Section E.3.9 - Standard Specifications).

It may be helpful in preparing specifications if users research details from previous purchases such as part/model numbers, prices and suppliers.

Procurement specialists will have standard specifications for certain regularly used items on a "specifications" file.

If the specification is wrong, inadequate or overly explicit it may result in:

• a suitable tenderer being precluded from bidding;
• tenderers wrongly or variously interpreting the requirement;
• tenderers failing to submit satisfactory tenders;
• major difficulties in evaluating the bids; or
• wrong or unsuitable goods/services being offered/supplied or services not meeting the true requirement.

Procurement specialists have the responsibility of challenging specifications that may be too restrictive or preclude the attainment of best value for money.

Procurement specialists may be asked to draw up or agree specifications, particularly in the case of regularly or widely used items. In these instances, the specification should be reviewed by the end users.

Wherever feasible, specialist purchasing staff should be brought into the discussions at the earliest possible stage of a purchase. They have a responsibility for referring back to the user any doubts they may have about the specification, description or recommended supplier recorded on the purchase requisition. They are also:

• experts (or have ready access to experts) in procurement and contractual law;
• able to advise on the most appropriate source of specialist specification advice and any legal constraints;
• able to provide access to existing specifications;
• familiar with the requirement for selecting the method of purchase;
• in a position to know whether the requirement is available under existing contracts;
• able to help with the development of an acquisition strategy;
• able to help with market research; and
• in a position to develop specific contractual clauses to complement the specification.

Any proposals to vary the specification (where agreed) require the consent of end users before tendering can takes place.

Taking a proactive approach and consulting colleagues with specialist purchasing knowledge throughout the specification development saves time and effort and ensures that you get what you want when you want it.

A standing specification should be reviewed periodically. Changes in working practices and technological developments cause obsolescence in existing specifications. A process should be established to ensure a regular review (at least once a year) of standing specifications ensuring requirements remain relevant to current needs and to the capabilities of the market.

Performance specifications describe the expected function or performance of the product or service. This enables tenderers to use their experience, and perhaps research & development investments, to offer the most cost-effective solution by responding flexibly and innovatively in offering the optimum (in terms of value for money) solution to the user’s requirements.

Basically a "performance" specification is one which focuses on the function of the product or service required: the specification is built around a description of what is to be achieved rather than a fixed description of how it should be done.

The performance specification must be clearly defined so that all tenderers fully understand the requirement and to enable the DTI to carry out an effective and fair evaluation of the bids.

The supplier can be held responsible, on the grounds of "unfitness for purpose" if the provision is not satisfactorily met or performed.

It is Government policy to issue, wherever possible, specifications on a "performance" basis rather than in design terms.

As the term implies, a design specification defines exact details of a good, e.g. the physical attributes, materials to be used, power input and output, the manufacturing processes required, or in the case of a service, the working methods to be used, and so on.

For some products and services, a design specification may be unavoidable: the nature of the requirement making it essential to narrow the options through a detailed full design specification. However, these assertions should be tested and specialist purchasers can help with this.

Where a design specification is justified, it should, wherever possible, be written around recognised British (for example BSI & BEAB) or equivalent European or international standard.

In the context of specifications, a "standard" is a technical specification or other document available to the public, drawn up with the cooperation and consensus or general approval of all interests affected by it. Standards are based on the consolidated results of science, technology and experience, aimed at the promotion of optimum commercial benefits and approved by a body recognised at the national, regional or international level.

The benefits of making use of a standard are:

• it represents the views of the whole of the market, both purchasers and suppliers;
• it represents a designation which, due to its commonality, is not unique in production or design; and
• it ensures, based on past experience, that the product or service is a tried and tested one.

The use of standards can eliminate the need to produce detailed technical features in specifications.

Buyers aiming to specify requirements in this way must however ensure that the standards claimed by suppliers actually apply to the product or service concerned – e.g. standards can appear on suppliers’ letterheads. Buyers must ensure that they question and understand the applicability of all standards before accepting them.

In the right circumstances, expressing requirements as a standard saves time and cost for buyer and supplier, and promotes good value for money. Buyers should however avoid the use of standards where they impose an unnecessary burden on suppliers, e.g. where they result in the over-specification of the goods or services required. This may also lead to the buyer paying more than necessary.

There is an order of precedence on the use of standards as follows: a European Standard; a European technical approval; a common technical specification; an international standard; a national standard; a national technical approval or agreement. In all cases, references to any of these standards in specifications must be accompanied by the words "or equivalent".

Where bids do not comply with a quoted standard, they cannot be rejected for that reason alone if the bidder can demonstrate that the proposal meets the requirement in an equivalent manner.

In addition to standards for specific goods and services, there are also standards that relate to quality and the management of quality. Perhaps the best known of these standards is ISO 9000.

Like a number of standards, ISO 9000 has various parts. ISO 9001 applies to design, manufacture and final inspection, ISO 9002 to manufacture and final inspection, and ISO 9003 to final inspection only.

DTI encourages best practice in business, quality, design and management. Purchasing staff should consider the circumstances in which it is be appropriate to require quality information from suppliers as part of a bid, what the quality requirement should be, and how it applies to the contract in question. For example, some suppliers have their own quality plans, which may be perfectly adequate to meet the contractual needs of the Department. Other contracts may require ISO 9000 - or equivalent – as an integral part of the bid.

If it is not possible to produce a detailed description, you may explain a requirement by issuing of samples or patterns to the supplier or requesting them from the supplier. In this case, a "standard" must be kept by the unit for later comparison with the supplied products. Samples, patterns and drawings may form part of a design specification.

It is good business ethics to return samples to the supplier that are not required for comparison purposes.

Care should be taken when using samples, patterns etc. for specification purposes, that Copyright is not breached.

Simplification and variety reduction techniques can reduce costs and encourage better value for money.

Simplification in a specification entails the elimination of complexities of design by omitting inessential details and, where possible, combining the functions of different details.

Variety reduction entails the purchase of the smallest possible number of different types, sizes or grades of products. At its simplest this might be seen as the reduction in the number of colours in which an item is purchased, or in the sizes of envelopes that are purchased or kept in stock.

• Are previous (similar or related) specifications available?
• Are the requirements clearly stated, concise, logical and unambiguous, containing only the essential features or characteristics of the requirement?
• Is the specification presented in performance terms rather than a detailed design?
• Do the specifications contain enough information for potential suppliers to design and cost the products or services they will offer?
• Are limits, tolerances or performance targets reasonable and easy to check? Are they written in such a way that they define the criteria for acceptance of offered products or services as well as permitting them to be evaluated by examination, trial, test or documentation?
• If appropriate, do specifications conform to European, international or national standards and comply with any legal obligations?
• Do specifications provide equal opportunity for all potential suppliers to offer a product or service which satisfies the needs of the user and which may incorporate alternative technical solutions?
• Ensure that specifications do not contain features that directly or indirectly discriminate in favour of, or against, any supplier, product, process or source.
• Ensure that they do not over-specify requirements - i.e. specify performance that is more than "Fit For Purpose".
• Have you taken due account of the Department’s environmental policies?
• Is variety reduction and simplification exercised?
• Are site-specific requirements necessary?