IBM AS/400 manual Subprocedure logic, Indicators, RPG IV Overview, The first, last

RPG IV Overview

.2/ RPG reads the next record and sets on the record identify control level indicators.

.3/	RPG	processes total calculations (conditioned by control level
	L1	through L9, an LR indicator, or an L0 entry).
.4/	RPG	processes all total output lines							(identified	by	a T in
	the	output	specifications).
.5/	RPG	determines if the LR indicator							is on. If it is on, the
.6/	The	fields of the selected input							records move from the rec
	essing area.			RPG sets	on	field		indicators.
.7/	RPG processes all detail calculations (not conditioned by cont
	indicators		in	positions	7	and	8	of	the calculation specificati
	the	data	from the record				at	the	beginning of	the	cycle.
The first	cycle

The first and last time through the program cycle differ somewhat f Before reading the first record the first time through the cycle, three things:

¹ handles input parameters, opens files, initializes program data

¹ writes the records conditioned by the 1P (first page) indicator

¹ processes all heading and detail output operations.

For example, heading lines printed before reading the first record constant or page heading information, or special fields such as PAGE a The program also bypasses total calculations and total output steps on cycle.

The	last	cycle
The	last time		a	program goes through	the cycle,		when	no	more	record
able,		the program sets the LR (last			record) indicator			and the			L1 t
level) indicatorson . toThe program processes the						total	calculations			and	tot
output,		then	all	files are closed, and then		the	program		ends.

Subprocedure logic

The general flow of a subprocedure is much simpler: the calculations cedure are done once, and then the subprocedure returns. There is generated for a subprocedure.

Indicators

An indicator is a one-byte character field that is either set on (' generally used to indicate the result of an operation or to conditi processing of an operation. Indicators are like switches in the flow logic. They determine the path the program will take during processin on how they are set or used.

Indicators can			be	defined	as variables on the definition specifica
also	use RPG	IV		indicators,	which are defined either by an entry
or	by the	RPG	IV program		itself.

Chapter 1. Overview of the RPG IV Programming5 Language