Picard allows users to write their own primitives and recipes for processing reduced data, although a number of (mostly SCUBA-2) recipes exist. Interested users are advised to read SUN/230 and SUN/233 for further details. The user can specify the environment variables ORAC_RECIPE_DIR and ORAC_PRIMITIVE_DIR to point to the locations containing recipes and primitives.
While Picard is designed to be instrument-independent, it is possible to access methods from supported instrument classes, provided that all the input data are from the same instrument. This is particularly useful for accessing instrument-specific values and methods provided by the calibration class, for example. It also provides access to instrument-specific recipes and primitives.