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Chapter 19 Introduction to Dialect Summary Micro Focus COBOL, which is implemented in this product, supports a number of dialects of COBOL. It consists of a base of ANSI'74 COBOL, which is always enabled, and the following optional dialects: * ANSI'85 COBOL * Data General Interactive COBOL * Micro Focus extensions * Microsoft V 1.1/IBM (PC) V 1.0 COBOL * Microsoft V 2.2 COBOL * IBM OS/VS COBOL * Ryan MacFarland RM/COBOL V2 * IBM VS COBOL II. In addition, the Report Writer facility may be enabled. IBM's SAA COBOL and the X/Open standard which are supported in Micro Focus COBOL are not described explicitly in this document.
NOTE This summary is included only for historical reference, and has not been updated since V2.2.
Both the ANSI'74 Standard and the ANSI'85 Standard allow implementors to include extensions to the COBOL language and explicitly describe the details of some features as implementor-defined. The resulting different versions of COBOL, or dialects, mean that moving a program from one compiler to another can involve a fair amount of work to amend it to the new dialect. To help overcome this problem, Micro Focus COBOL incorporates many of the most widely used dialects of COBOL. The COBOL compiler cannot simply accept all features of all these dialects unconditionally, because a word available for use as a user-defined word in one dialect may be reserved in another. So the compiler treats the dialects as alternatives; it accepts dialect control directives, which reserve particular sets of words needed for particular dialects. (See your COBOL System Reference for a description of directives.) Some dialect control directives can be used as operands in the FLAG directive. This makes the compiler flag any feature that is not in the selected dialect. Flagging a feature means the compiler allows it, but displays a message to draw the programmer's attention to it. Generally, if a feature from some dialect does not need extra reserved words, it is always accepted by the compiler. However, in certain cases, the same source code may produce different results in different dialects. For these cases, use other language-affecting directives to control the behavior of specific features. Some installations may not want to use the few directives which disable certain features. The compiler treats COBOL as defined in the ANSI'74 Standard (excluding the Report Writer module) as the base language. Whatever dialect control directives are set, all features that appear in the ANSI'74 Standard (excluding Report Writer) are accepted. For convenience, the ANSI '85 Standard and the Report Writer module of the ANSI'74 Standard are treated as dialects. The Micro Focus COBOL language has developed over the years, with features being added at intervals, but always with compatibility with earlier versions paramount. The different levels of COBOL functionality resulting from this process are known as language levels. This reference contains useful information for users of products developed by Micro Focus as it indicates in which product each feature first appeared. The dialect control directives for some dialects can be followed by a number; this classifies as reserved words only the words needed for the features implemented in a particular language level. The tables in this reference list all features of Micro Focus COBOL that do not appear in the ANSI'74 Standard. The features are divided according to the dialect(s) in which they appear. These tables also list the language level at which each feature was introduced and indicate directives which enable particular behavior.