1 File_Format GILDAS is based on a virtual memory system which recognises a unique file format. This format may however be used for storing two somewhat different kinds of data : 1. IMAGES : Images are regularly sampled 2-d, 3-d or 4-d data which require conversion formula for the coordinates along each axis. Data values may be Integer, Real or Double precision, but most algorithms support only REAL images. 2. TABLES : Tables are ensembles of columns strictly equivalent to the formatted files used by GreG as input for the X,Y,Z buffers (indeed GreG is also able to read and write Tables). The only difference is that they are unformatted, and hence access time is typically 50 times faster... The number of lines is fixed, but the number of columns may be extended indefinitely. In fact, a table may be consider as a 2-D image (and vice-versa if you want) but does not require "axis" information... Tables and Images may be produced by other softwares (mainly CLASS if one considers that GreG is a subset of GRAPHIC), and fully manipulated by the GILDAS environnement. They can be used in mathematical formulae in SIC monitor. 1 END