Technical specifications as formal documents in themselves can be either descriptive or persuasive; the term is used differently depending on the industry and situation.

Technical Specifications as Descriptions

Technical specifications may be descriptions of existing products or product requirements. They provide details for the design, manufacture, testing, installation, and use of a product; they are a specialized type of description.

You typically see technical specifications in the documentation that comes in the package with certain kinds of products such as computers. Specifications describe the key technical characteristics of the item. But specifications are also written as a way of specifying the construction and operational characteristics of an object. They are then used by people who actually construct the object. When you write technical specifications as descriptions, accuracy, precision of detail, and clarity are critical. Poorly written specifications can cause a range of problems and lead to lawsuits.

Graphics, tables, and lists feature prominently in technical specifications. Use graphics wherever they enable you to convey information more effectively. For example, in the specifications for a cleanroom for production of integrated circuits, drawings, diagrams, and schematics can convey some of the information much more succinctly and effectively than sentences and paragraphs.

Many technical specifications use a two-column layout in lists or tables to offer specific details. If the purpose is to indicate details such as dimensions, materials, weight, tolerances, and frequencies, for example, regular paragraph-style writing may be unnecessary. For graphs and tables, you can use either the open (performance) style in which you specify what the component can do, or the closed (restrictive) style, in which you specify exactly what the component should be or consist of. Other descriptive technical specifications exist in outline format; again, regular paragraph-style writing may be unnecessary.

However, some details can only be provided through sentences and paragraphs. If you need to write fuller descriptive technical specifications, consider the following content, organization, and style suggestions:

• Introduction and General description – Describe the product, component, or program first in general terms. Include administrative details about its cost, start and completion dates, overall description of the project, scope of the specifications (what you are not covering), and anything else of a general nature which will not fit logically in the part-by-part descriptions that follow.
• Part-by-part description – In the main body, present specifications part by part, element by element, trade by trade, or whatever is logical, natural, or conventional to the industry. (Find out what the specific requirements are for format, style, contents, and organization in your company or industry; talk to others and/or get samples.)
• General-to-specific order – Wherever applicable, arrange specifications from general to specific.
• Use specific, concrete language that identifies as precisely as possible what the product or component should be or do. Avoid ambiguous words that can be interpreted in more than one way. Use technical jargon the way it is used in the trade or profession.
• Provide numerical specifications in both words and symbols: for example, “the distance between the two components shall be three centimeters (3 cm).”
• Writing style in specifications can be very terse; incomplete sentences are acceptable as well as the omission of functions words such as articles and conjunctions.

Test all descriptive technical specifications by putting yourself in the role of a bumbling contractor, or even an unscrupulous one. What are the ways in which a careless or incompetent individual could misread your specifications? Could someone willfully misread your specifications in order to cut cost, time, and thus quality? Obviously, no set of specifications can ultimately be foolproof, but you must try to make them as clear and unambiguous as possible.

Read a sample specification on Energy Smart Design.

Technical Specifications as Persuasion/Proposals

Technical specifications can also function as persuasive documents—sometimes proposals—that show your client or team members what problem you’re solving, the goals or requirements for your project or product, and how you plan to achieve this. Persuasive technical specifications direct the work to be accomplished, and sometimes are rewritten as the project progresses.

If you need to write persuasive technical specifications, consider the following content and organization suggestions:

• Introduction and Overview – Start with a summary of what you’re doing. Explain the problem, then summarize what the project or product is and what it will do. Next, explain what your approach for solving the problem will be and include product specs if you’re dealing with equipment. Link to any marketing or engineering documents that are important to the project. Finally, provide a rough time estimate for how long it will take to finish the project or product.
• Goals – Briefly outline the goals you plan to accomplish with your project or product. This could be as brief as a lead-in statement, with a following numbered or bulleted list of goals.
• Scope of Project – Explain things that are outside of the scope of the project. This includes work that you will not do, solutions you don’t think will work well, and attributes your product or project will not have. Be thorough to reduce misunderstandings by your client or team.
• Product Requirements –  Explain the things your project or product needs to do to solve your problem.
• Plan/Approach –  Describe how you will solve the problem or the different approaches you are considering if a final decision hasn’t been made. Explain your research and each technology or process that you will use. If possible, include illustrations, charts, and diagrams so that it’s easier for your readers to understand your plan. Finally, discuss how you will test your plan and what you will do if there are issues. If you describe different approaches or technologies, create a subsection for each one so that your plan is easy to follow.
• Other Options Considered – Describe the other options you considered but ruled out. Explain why you ruled out each option.
• Open Questions (Optional) –  Include this section if you have unresolved issues. Your technical specification should focus on the product or project so that your client understands what they’re getting and your team is working on the same goals. Don’t worry about including every detail or answering your “to be determined” questions. Instead, present a  list or brief discussion of the things you’ll decide later.
• Methods of Evaluation – Describe your methods and metrics for evaluating the product or project. Include this information in one section or multiple sections. In one or more paragraphs, explain how you will make sure your product or project is working correctly and accomplishing your goals. Additionally, describe how you will check for bugs or problems. Include the specific analytical processes or technologies you’ll use.
• Security and Privacy (Optional) – If appropriate, briefly describe any risks and how you will secure your system so privacy is protected. Write a couple of paragraphs to explain your methods.
• Timeline and Milestones – A timeline helps keep your project on track and tells both your client and your team what needs to be done. Break down the tasks according to who is doing them and when they will be done. Include a list for each team or team member, if appropriate. For instance, a task breakdown might list Engineering Team, Planning Team, Marketing, and Quality Assurance.

Note that content and organization depend on your company, client, and/or the product or process itself. For another slightly different structure for writing persuasive technical specifications, see A practical guide to writing technical specs.