What are the limitations when it comes to creating/editing target data extension fields?

When using the Edit Target Data Extension functionality or when using the Create Data Extension functionality, the following limitations apply:

- Field Length can only be changed for field type Text.
- When creating a data extension, Primary Key and Nullable can be changed without limitations until the data extension is created. When editing a data extension, Primary Key and Nullable can be changed only if a field does not have Primary Key or Nullable checked.
- A Default Value cannot be set for Email Address, Phone and Locale fields.