A scrolling list can display data stored in a repeating group view. Use scrolling when the maximum cardinality of a group view exceeds the number of display lines available on the screen.
The screen, or presentation space, displays fields, literals, and special fields.
The area of the screen where the repeating group view is displayed is called the presentation view. Data in the presentation view that is visible to the user is called the viewport.
The size of the repeating group view equals the cardinality of the view. This size is referred to as the data view extent. The maximum cardinality of the repeating group view defines the total number of entries that can be present in the repeating group. This sets the size of the data view extent in memory.
The size of the viewport is based on the number of rows it contains. This size also is known as the placed cardinality. The viewport can originate at any row in the data view extent. The row in the data view extent that is the first row in the viewport is called the viewport origin. This is an index number identifying the row in the data view extent that is to be mapped to the first row in the viewport. All subsequent rows are mapped from that point.
The data view encompasses all of the occurrences in a repeating group view. The data in a repeating group must be stored in memory in a table or in an array of data items. The entire collection of scrollable data can be up to 32 bytes in length, including the overhead of the view and other variables within the view.
The data population size is the number of rows actually populated in the repeating group view. Also called the current cardinality, this value can range from zero to the data view extent size. The data population size cannot be greater than the data view extent size, nor can it be a negative number.
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