It has the same meaning as the DataWindow buffers in PowerBuilder.
When data is retrieved from the database, it is retrieved into the primary buffer.
The data in the primary buffer represents data that has not been deleted or filtered out.
When a row in the primary buffer is modified, its value which was originally retrieved from the database is copied into the original buffer from the primary buffer. The value is copied only when the row is modified for the first time.
When a row in the primary buffer is deleted, it is moved to the delete buffer.
The data in the delete buffer represents data that has been deleted but has not been committed to the database.
When rows are filtered, the rows that do not meet the condition are moved from the primary buffer to the filter buffer.
The data in the filter buffer represents data that has been removed from view.