I want to know the linage of each field used in each sheets. For example, if I place "Products"."Product line" column in a chart, I want to know where does this column come from the datasource, e.g. from EDS database, Sales schema, Products table and Product_line column. Extensions API provides methods to access data, but I did not see any way to access metadata. I can see all metadata information is stored in .tdb file, but no way to access them via extensions API.