Occurrence
Occurrence determines the number of times a field is present in a record. If blank, APPX assumes a value of 1. This field may contain up to five numeric characters and is restricted to a maximum of 32,767.
A multiple-occurrence field is simply an alternative to defining multiple fields in a file. For example, a balance record in a General Ledger application may contain an ending balance field that is repeated 12 times, one for each month in the year. You could define 12 fields, January Ending Balance, February Ending Balance, March Ending Balance, and so on, or you could define one ending balance field with 12 occurrences.
APPX considers each occurrence as a separate field, uniquely identified by the combination of application ID, field name, and occurrence number. Each occurrence of a multiple-occurrence field is no different from a single-occurrence field in that:
APPX allocates unique physical storage for each occurrence.
You can paint a specific occurrence on an image.
Statements operate on specific occurrences of a field.
Unlike separate fields, however, if a multiple-occurrence field is included in a group, all occurrences become part of the group. It is not possible to selectively include specific occurrences in a group, while excluding other occurrences. However, see Special Uses for Group Fields for some creative ways to manipulate groups and occurrences.
There are two primary advantages of using multiple-occurrence fields. Multiple-occurrence fields:
Minimize the effort that is required to define the data dictionary. You enter a single field definition rather than a separate field definition for each occurrence.
Minimize the effort that is required to manipulate data using APPX statements.
You can exert less control over multiple-occurrence fields than you can over single-occurrence fields because you:
Must include all occurrences in a group.
Cannot define a synonym for a multiple-occurrence field.
Cannot establish a multiple-occurrence substring.
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