Multiple master fonts (MM fonts) – were an extension to Adobe Systems' Type 1 PostScript fonts, now mostly superseded by the advent of OpenType. Multiple master fonts contain two or more «masters» — that is, original font styles — and enable a user to interpolate between these masters along a continuous range of «axes.» With proper application support, these axes can be adjusted on demand. From one MM font, it is conceivable to create a wide gamut of typeface styles of different widths, weights and proportions, without losing the integrity or readability of the character glyphs.