*Conan The Librarian
expression Defines the test to be performed. The expression can consist of one or more numeric constants, string literals, symbolic names, or lexical functions separated by logical, arithmetic, or string operators. Expressions in IF commands are automatically evaluated during the execution of the command. Character strings beginning with alphabetic characters that are not enclosed in quotation marks (" ") are assumed to be symbol names or lexical functions. The command language interpreter (CLI) replaces these strings with their current values. Symbol substitution in expressions in IF commands is not iterative; that is, each symbol is replaced only once. However, if you want iterative substitution, precede a symbol name with an apostrophe (') or ampersand (&). The command interpreter does not execute an IF command when it contains an undefined symbol. Instead, the command interpreter issues a warning message and executes the next command in the procedure. For a summary of operators and details on how to specify expressions, see the OpenVMS User's Manual. command Specifies the DCL command or commands to be executed, depending on the syntax specified, when the result of the expression is true or false.