This user's manual guides you through the radar interferometric processing with the Doris software. A user will be able to process ERS1/2, ENVISAT, JERS, RADARSAT, ALOS and TERRASAR-X data with the aid of this manual. The data must be in Single Look Complex format (SLC). Doris is not a SAR processor, i.e., you cannot process/focus RAW radar data. The manual also contains implementation specifications which can be helpful to a programmer for further development of Doris, or to understand WARNING and ERROR messages.