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The best of a dozen different methods for compressing map data is illustrated. The choices are generated by encoding data strings—sequence of like codes—by three methods and in four directions. Relationships are developed between compression alternatives to avoid comparing all of them. The technique has been used to compress data from forest resource maps, but is widely applicable to map and photographic data reduction. [ABSTRACT FROM AUTHOR]

Cryptographic techniques which can be used to maintain the confidentiality of information processed by computers are dealt with. Special emphasis is paid to the unique characteristics of computer files that make many cryptographic methods of little use. Relative security, costs, and preferred methods are included in this paper. [ABSTRACT FROM AUTHOR]

The article focuses on the U.S. Standard Data Code for Calendar Date for Machine-to-Machine Data Interchange. The purpose of this standard is to provide a standard means of recording calendar date to facilitate interchange of data between the machines of data systems. Calendar date is a data group identifier composed of the data elements year of century, month of year, and day of month. Year of century shall be encoded by the two low order digits of the conventional numeric designation of the Gregorian calendar year. The Standard Data Code for Calendar Date is intended to be a member of a family of data codes for time to be developed for the full range of needs for data codes for time in the interchange of data between the machines of data systems. The high to low sequence of data elements is proposed for the following reasons: It is consistent with the sequence of data element codes already used in identifying other times; it provides a foundation for building a system of identifiers to times; it is consistent with the sequence of individual identifying terms used essentially universally in other subject areas.