A program specification is the definition of what a computer program is expected to do. It can be informal, in which case it can be considered as a blueprint or user manual from a developer point of view, or formal, in which case it has a definite meaning defined in mathematical or programmatic terms.
... there are 5,013 people, 1,455 households, and 1,223 families residing in the town. The population density is 1,433.7/km² (3,704.7/mi²). There are 1,494 housing ...