Selective full text indexing (Oracle text) of specific documents

How do the users out there selectively full text index documents? We have both user generated documents as well as system generated reports, and the latter have additional metadata fields added for the spaces application to display/order, search on, and in this case we want to selectively exclude the contents of the reports from full-text indexing...as indexing numeric values, and other text within the reports would not be useful for searching, and adds greatly to the sizes of the ft_idctext1 and ft_idctext2 indexes, fast, full index optimization etc. The file format exclusion will not work for us as these are