Table1.AddIndex('SomeField', 'SomeField', []);

Another way is to use the local SQL statement CREATE INDEX. Execute the
statement from a TQuery using its ExecSQL method.

  CREATE INDEX SomeField ON TableName (SomeField)

Local SQL (what the BDE uses for dBASE, Paradox, and FoxPro tables) is
documented in the online help file LOCALSQL.HLP, found in the main BDE
directory. This help file is a language reference of the local SQL
implementation (subset) of SQL-92. The copy of this file that came with BDE
4.x (and earlier versions) was outdated and has since been rewritten.
Updated copies will have the topic "Unsupported language" in the index (and
lack of this topic indicates a pre-update copy). I can e-mail you a copy of
the updated file if you need and desire it.

And still another way is to use the BDE API function DbiAddIndex,
documented in the BDE API help. But as the TTable.AddIndex method is a
wrapper around this API function, there is seldom a pressing need to use
it.

   Add('ProfileListIndex', 'ProfileNumb' , []);

I always get "Invalid index/tag name".