ISO/IEC 9995 defines a framework for the layout of all alphanumeric and numeric keyboards across the widest spectrum of today's and upcoming applications using keyboards. The functions to be performed by keyboards are grouped into three categories that correspond to the main physical sections of the keyboard.

Application of ISO/IEC 9995 in the design of keyboards will provide the user with a unified, predictable user-machine interface by dividing the keyboard into functional areas and sections and allocating functions to keys.

ISO/IEC 9995-8:2009 specifies the allocation of letters to the keys of the numeric zone ZN0 of a keyboard which has the ten digits zero to nine allocated in the "1-2-3" layout. The layout specified in ISO/IEC 9995-8:2009 is intended for applications of information technology equipment keyboards where letters instead of digits are used for the mnemonic retention of numeric information.