In identifying an essential function to determine if an individual with a disability is qualified, the employer should focus on the purpose of the function and the result to be accomplished, rather than the manner in which the function presently is performed. An individual with a disability may be qualified to perform the function if an accommodation would enable this person to perform the job in a different way, and the accommodation does not impose an undue hardship. Although it may be essential that a function be performed, frequently it is not essential that it be performed in a particular way (EEOC, 1992).
According to Torrington, a job description is usually developed by conducting a job analysis, which includes examining the tasks and sequences of tasks necessary to perform the job. The analysis considers the areas of knowledge and skills needed for the job. A job usually includes several roles. According to Hall, the job description might be broadened to form a person specification or may be known as "terms of reference". The person/job specification can be presented as a stand-alone document, but in practice it is usually included within the job description. A job description is often used by employers in the recruitment process.