Index instruments are identified by the field type and the values within the field.
If the Product field of the Instrument block is present and has the value 7 (INDEX), then the instrument is an index.
If Product is not present, but Security Type is present and has the value INDEX, then the instrument is an index.
If both Product and Security Type are not present and the CFICode field is present 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), then the instrument is an index.
Otherwise, this is not an index.