A Pattern is an abstract representation of a sewing pattern. A pattern can be created and managed using the frontend. This frontend allows for drawing patterns. This draw data is stored in another object called PatternData. A Pattern stores a pointer to the latest PatternData object. So the latest version is always available. The PatternData object stores the actual draw data. This draw data is stored as a JSON string. The frontend can use this JSON string to draw the pattern. The frontend can also use the JSON string to export the pattern to a PDF file.