The first page (1P) indicator is set on by the RPG IV program when the
program starts running and is set off by the RPG IV program after detail
time output. The first record will be processed after detail time output.
The 1P indicator can be used to condition heading or detail records that are
to be written at 1P time. Do not use the 1P indicator in any of the following
ways:
To condition output fields that require data from input records; this
is because the input data will not be available.
To condition total or exception output lines
In an AND relationship with control level indicators
As a resulting indicator
When MAIN or NOMAIN is specified on a control specification