The section describes the layout of the reference section that follows. The reference section provides a detailed description in alphabetic order of all the elements that comprise JAL.

This section provides information about the following topics:

• Introduction
• Page Layout
• Syntax Notation Conventions

Introduction

While JAL is a very simple language incorporating only a few statement types, it is also rich in Descriptors, the elements from which the power of JAL is derived. In order to use JAL, it is not necessary to be familiar with all Descriptors, which make up the bulk of the following descriptions.

JAL can be learned quickly by reviewing the case study provided in the companion manual DAL/JAL User Guide as your starting pattern. In this manual, JAL Statement Summary provides a summary of all JAL statement types, and in Descriptors by Area you can find summary tables of all JAL Descriptors organized by area of interest.

Once you are ready to code JAL, you will identify the Descriptors you need, and only then are detailed descriptions necessary. To make your task easier, the detailed descriptions are organized alphabetically in the following section.

Page Layout

This section uses a standard page layout to document all JAL statements. This approach provides all necessary information in one convenient location. The page layout is illustrated below.

The numbered page areas are used as follows:

 1.  The JAL statement name or Descriptor name is boxed in the upper left corner of the page. Also a title, or expanded name, appears under the boxed statement or Descriptor name.

 2.  The “Type” indicates the type of statement or descriptor.

 3.  The “Maximum Length” area indicates how many characters there are for a character string Descriptor. For a Range Definition Descriptor, the size of the number that can be specified is indicated.

 4.  The next section gives a full description of the statement or Descriptor, usually one or two paragraphs.

 5.  A model of the syntax or format is next. This is boxed for easy identification. Within the format box, the notation conventions described below are used.

 6.  The format box is followed by a detailed explanation of the operands as shown in the format.

 7.  “Usage” indicates which statement types allow you to use the Descriptor.

 8.  “Examples” provides specific examples of use.

 9.  “See Also” refers you to other related statements or Descriptors.

 10.  “Notes” provides details about syntax, restrictions, or other information.

Syntax Notation Conventions

In the descriptions, a model of the statement or Descriptor is presented in a highlighted format box. Within these format models, the following notation conventions apply:

• Uppercase letters and words are coded exactly as they appear in the format model. So are the following characters:

comma ,
parentheses ( )
period .

• Lowercase letters, words, and symbols appearing in the format model represent variables. When you code the parameter, substitute specific information. For example:

is part of the format description for the $INDEVICE Descriptor. When you code this Descriptor, substitute a character string which is a valid input device. A typical example:

• Brackets [ ] are a special notation and are never coded on a statement. Brackets indicate that the enclosed item is optional and you can omit it entirely. For example:

Vertical bars | are a special notation and are never coded on a statement. These bars are used to separate elements of a set of items from which you must choose only one. For example:

Here you must choose either YES or NO.