There is a property called Ordinal that appears in a few models including
PayOptions , PaySchedule and PayRun .
It also appears as an optional parameter on a number of operations.
TL:DR: You can safely ignore this value and/or leave it with its default value of 1
By default there is a PaySchedule for each PayPeriod - so one for monthly, one for weekly and so on.
For the majority of users this is sufficient.
But some users require multiple schedules of the same PayPeriod for the same employer.
For example they may have two Monthly pay runs:
It's that scenario that the Ordinal property is designed to support.
For the above example you'd set the usual Monthly schedule for employees and set the employees
to use it by setting their PayOptions PayPeriod to Monthly and just ignore the Ordinal property so it has its default value of 1.
For Directors you'd do the same, but set the Ordinal to 2. This would create a new PaySchedule (which you'd need to configure)
When it comes to interacting with this schedule - starting/getting PayRuns , running reports - you'll need to specify the value of 2 for the optional Ordinal paramter.