IFF, the "Interchange File Format" standard, encourages multimedia interchange between different programs and different computers. It supports long-lived, extensible data. It's great for composite files like a page layout file that includes photos, an animation file that includes music, and a library of sound effects. IFF is a 2-level standard. The first layer is the "wrapper" or "envelope" structure for all IFF files. Technically, it's the syntax. The second layer defines particular IFF file types such as ILBM (standard raster pictures), ANIM (animation), SMUS (simple musical score), and 8SVX (8-bit sampled audio voice). IFF is also a design idea: programs should use interchange formats for their everyday storage. This way, users rarely need converters and import/export commands to change software releases, application programs, or hardware.