Importing Flat Files without undefined data and using Defaul

I’m currently trying to use a flat file adapter to import and parse a flat file for inserting records into JDEdwards using the webMethods toolset. During the importing of records from the flat file, I get errors with error code of 11 and also lot of unwanted data in the undefined tab. How can I filter my flat file data and import only the required records using the webMethods flat file adapter?? An urgent response is greatly appreciated.