Character Representation

The text within an SCL source file falls into three broad categories:

1. SCL commands.
2. Arguments to SCL commands - variable names, integer values or quoted character strings, for example.
3. Comments, to improve legibility and maintenance.

Within character string arguments, SCL supports the use of any character with an ASCII value in the range HEX 00 to FF inclusive. However, direct specification of these characters is not always possible, for two reasons:

1. Characters with values in the ranges HEX 00 to 20 and HEX 7F to A0, and the value HEX FF, are `non-printing' characters, and cannot easily be specified in an SCL source file.
2. Two characters are reserved for use by SCL - one as a command character and the other as a control character. The characters used for these purposes cannot be used as literal characters in a character string. The default values are "~" for the command character and "^" for the control character; these values are used throughout these instructions. They can, however, be changed within the script.

To resolve these problems, SCL provides a set of `character commands', as described in Representing the Command Character and Representing the Control Character. In addition, to ensure there is no ambiguity within the source file, characters are rejected which have values in the ranges HEX 00 to 20, or HEX 7F to A0, or the value HEX FF, except as described in Characters Ignored by the Compiler.

Character commands are recognized within all SCL character strings (except for a small number of exceptions that are explicitly stated). Thus, for example, the character string "~<07>" always represents a single character (namely the character with a hexadecimal value of 7), not five characters.

Note: Single quotes may be included in character strings by using double quotes for the string delimiters, and vice versa.

See also:

Character Command Using Hexadecimal ASCII Code

Character Command Using ASCII Mnemonic

Control Command

Representing the Command Character

Representing the Control Character

Overview of Script Control Language Syntax