Most of the items which are used to build up an image follow a FITS-like convention. For example the number of axes in an image is given by the naxis item, whereas the number of pixels along each axis is given by item naxis i. Three exceptions are the image, mask and history item. The image item contains the pixel data, stored as floating point numbers. The mask item, if present, contains a bit-mask used for pixel blanking -- MIRIAD does not use magic value blanking like AIPS . Finally the history item contains a text file describing the history of the dataset.
A complete list of the items that are potentially contained within an image dataset is given in Appendix B.