Points to the list of field definitions for the dataset.
property FieldDefs: TFieldDefs;
FieldDefs lists the field definitions for a dataset. While an application can examine FieldDefs to explore the field definitions for a dataset, it should not change these definitions unless creating a new table with CreateTable or CreateDataSet.
To access fields and field values in a dataset, use the Fields, AggFields, and FieldValues properties, and the FieldsByName method.
Note: If the dataset includes object field descendants, FieldDefs represents a hierarchical view of the data, meaning that the definitions include object field definitions. To determine the definitions in a flattened view, use FieldDefList instead.