Ada 9X Project Report. Character Set Issues for Ada 9X. October 1989

摘要

Issues and design considerations relevant to the introduction of large and/or multiple coded character sets in the Ada language definition are presented. Emphasis is on identifying and understanding design and implementation considerations. Some recommendations are made. During balloting on the ISO draft international standard for Ada (ISO DIS 8652) conducted in 1986, two comments (neither part of a negative vote) indicated that Ada should be adapted to allow use of coded character sets other than ASCII. Both Japan and Czechoslovakia urged that Ada be adapted to allow the use of so-called national replacement character sets as part of the next revision of Ada. ISO JTC1/SC22/WG9 agreed that this proposal should be considered in the next revision. The draft standard was approved without modification, and became known as ISO 8652-1987 Programming Language Ada. Now that the revision process for the ANSI, and thereby the ISO, standards is in progress under the leadership of the US Department of Defense, it is appropriate to explore the issues involved in adapting the Ada language definition to deal with coded character sets other than ASCII. This report is organized in two main parts. Section 2 provides a brief overview of the world of coded character sets. This material provides background for the following main part. Section 3 provides a survey of the various design issues that must be considered for the Ada language. Where possible, approaches that are promising as a basic for incorporation in Ada 9X are recommended. (KR)