The first check performed by the batch daily planning programs
is to ensure that a network has at least a first operation (FOP) and
a last operation (LOP).
Suppose you have a plan with the following operations and dependencies:
Application A, operation 001, predecessor of B, operation 002
Application B, operation 002, predecessor of C, operation 003
Application C, operation 003, predecessor of A, operation 001
Application D, operation 004, predecessor of E, operation 005
Application E, operation 005, LOP
Application F, operation 006, predecessor of E, operation 005
In this example, network 2 has two first operations (FOP) and one
last operation (LOP), which is allowed. Network 1, instead, has neither
FOP nor LOP, which means that a loop condition will surely occur.
When processing the network, batch daily planning programs detect
the loop and issue the message EQQ3150E in the EQQMLOG and EQQLOOP
data sets, specifying NO ENTRY AND/OR EXIT POINT as loop type. In
the system log, the message EQQ3163E indicates that a loop condition
has occurred.