Mapping ADO DataTypes to Delphi DataTypes

I have used ADO OpenSchema(siColumns ...) to get table columns and
their datatypes. This method brings back numerics for the data type. I
am using the Microsoft.Jet.oledb.4.0 provider. The data source is an
Access database.

Question: How do I map these numbers to the ADO data types such as
adChar, adEmpty, etc., so I can then relate them to Delphi data types
such as ftInteger, ftString, etc.? If I use adChar in a relation test,
I get an undeclared/undefined error. What don't I understand?

Any help will be greatly appreciated.