A.6.2—
Structured Representations

Computer design and programming can and does make use of syntactic structures to which the computer is sensitive as well. In programming, for example, it is common to create complex representational structures by combining simpler ones. Suppose, for example, that a researcher in the social sciences is engaged in an experiment in which he uses a questionnaire with fifty true-false questions. He wishes to store the results of the questionnaire in a data base and then run several statistical analysis programs on his data, and wishes to index the answers from each questionnaire by the Social Security number of the participant. An efficient and intuitively appealing way of organizing the data is to think of the information from each questionnaire as one record, and the entire data base as a series of records. Each record holds an encoded social security number and fifty representations of answers to questions.

Such a record could be stored by means of a complex marker structured in the following way: (1) a series of nine seven-bit locations holding the ASCII encodings of the digits of the Social Security number, followed by (2) a series of fifty one-bit locations holding representations of the boolean values true (represented by a 1-state) and false (represented by a 0-state). What has just been articulated is a convention for a complex data type. The convention specifies not only the coding and representational schemes to be employed, but the syntactic structure of the record as well. And this sort of syntactic structure the programmer would assure that his program was sensitive to, since he wants to be able to have access to different kinds of information and wants to be able to perform different operations on different kinds of information.