Prior to STx 3.0, all STx metadata was stored in so-called SD0 files - files with the extension 'sd0'. Each wave file opened in STx was associated with an SD0 file, (e.g. TheMarrageOfFigaro.wav was associate with TheMarrageOfFigaro.sd0 in the same directory). If the file existed, the metadata was imported into STx and saved on exiting (or explicit saving), otherwise, the file was created. It was possible to associate more that one SD0 file with a wave file by incrementing the number (e.g. TheMarrageOfFigaro.sd1, TheMarrageOfFigaro.sd2 etc). When migrating sound files, SD0 files had to be migrated too.
SD0 files since STx 3.0
The SD0 format has been replaced by a new metadata format stored using the XML format. Support for SD0 files has been reduced to SD0 import, if no corresponding XML metadata exists for this sound file.
Note: SD0 files have been superseded by project files.