The FieldDefs property lists the field definitions for a dataset. While an application can examine FieldDefs to explore the field definitions for a table, it should not change these definitions unless creating a new table with the CreateTable method. To access fields and field values in a table, use the Fields property and the FieldByName method. If the FieldDefs property is updated or manually edited, the StoreDefs property is automatically set to True.
The field definitions in the FieldDefs may not always reflect the current field definitions available for a table unless the table has been opened. Before using the field definitions from an existing table for in a call to the AlterTable method, call the Update method to read the field definitions from the actual table.