An indicator is a one-byte character field that is either set on ('1') or off ('0'). It is generally used to indicate the result of an operation or to condition (control) the processing of an operation. Indicators are like switches in the flow of the program logic. They determine the path the program will take during processing, depending on how they are set or used.
Indicators can be defined as variables on the definition specifications. You can also use RPG IV indicators, which are defined either by an entry on a specification or by the RPG IV program itself.
Each RPG IV indicator has a two-character name (for example, LR, 01, H3), and is referred to in some entries of some specifications just by the two-character name, and in others by the special name *INxx where xx is the two-character name. You can use several types of these indicators; each type signals something different. The positions on the specification in which you define an indicator determine the use of the indicator. Once you define an indicator in your program, it can limit or control calculation and output operations.
Indicator variables can be used any place an indicator of the form *INxx may be used with the exception of the OFLIND and EXTIND keywords on the file description specifications.
An RPG program sets and resets certain indicators at specific times during the program cycle. In addition, the state of indicators can be changed explicitly in calculation operations.