Expressions

To achieve maximum benefits from the product, you need to understand how expressions are used. An expression evaluates to a target address and can optionally denote the length of the data at that address. Expressions are evaluated in the context of the target address space.

Address expressions consist of one or more terms, separated by an operator. The first term can be a previously defined symbol. Each term can be suffixed with one or more indirection indicators. The expression ASCB+6C?+C0 contains three terms: ASCB, 6C?, and C0, which are separated by the plus sign operator. (The minus sign is also supported.)

In the example ASCB+6C?+C0

• ASCB is a predefined symbol that represents the address of the ASCB control block for the target address space.

  For more information about symbols, see Symbols. SYSPROG Services currently provides approximately 150 predefined symbols. You can also use the EQUATE service to define your own symbols. For more informaiton, see EQUATE.

• 6C? is a term consisting of a hexadecimal value (6C), followed by an indirection indicator (?).

  For more information, see Indirection-indicators.

• C0 (a hexadecimal value) is another term. You can also express values in decimal by appending an N to the decimal value. For example, 192N has the same value as C0. Additional numeric scaling suffixes are also provided. See Scale-suffixes.
• If the first term is a symbol, the target address space attribute of the expression is inherited from that symbol. The exception is if the expression is explicitly overridden by specifying another target address space name with another parameter on the command.

In the example DUMP,XYZ+8,20 , SYSPROG Services targets the address space implied by symbol XYZ.

In the example DUMP,XYZ+8,20,ABC, SYSPROG Services targets the address space ABC because ABC is an explicit reference.

For more information, see EQUATE.

The following topics provide detailed information about SYSPROG Services accept: