Index instruments are identified by field types and values within the field.
If the Product field of the Instrument block is present and has the value 7 (INDEX), the instrument is an index.
If Product is not present, but Security Type is, and has the value INDEX, the instrument is an index.
If neither Product nor Security Type are present, but the CFICode field is, and the first character of the field is M (for Miscellaneous), and the second letter is one of R (for Referential) and the third letter is I (for Indices), the instrument is an index.
Otherwise, this is not an index.