The GlowIcons format, based on NewIcons file format, is the native icon format used in AmigaOS 3.5, 3.9 and 4.0 by Matt Chaput. The major difference to NewIcons is how image data is stored. NewIcons uses inefficient ASCII encoding embedded to the application Tool Type metadata. In GlowIcons system developers extended internal icon definition without need to resort to storing information as Tool Types. The standard icon size is 46×46 pixels with maximum 256 (8-bit) colors and two image states (example: open and closed drawers). The second image state uses a glow effect to indicate that the icon is pressed.