ISO/IEC 9995定义了一个框架，用于在当今和未来最广泛的使用键盘的应用程序中，所有字母数字和数字键盘的布局。键盘要执行的功能分为三类，分别对应于键盘的主要物理部分。 ISO/IEC 9995在键盘设计中的应用将为用户提供统一、可预测的用户-机器界面，方法是将键盘划分为功能区域和部分，并将功能分配给按键。 ISO/IEC 9995-4:2009规定了键盘的数字部分以及该部分的分区。 它规定了数字区ZN0和功能区ZN1至ZN6中键的排列、编号和位置，以及键的功能分配。 数字区ZN0将用于文本和数据处理、通用办公环境、银行、销售点（POS）、远程信息处理服务、电话设备、家庭电子系统、机械和设备的数字控制以及个人识别码（PIN）输入等应用的键盘。功能区ZN1将用于数据输入、文本和数据处理以及通用办公环境等应用的键盘中。

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 9995-4:2009 specifies the numeric section of a keyboard and the division of that section into zones. It specifies the arrangement, the number, and the location of the keys in the numeric zone ZN0 and in the function zones ZN1 to ZN6 of the numeric section, as well as the allocation of functions to the keys. The numeric zone ZN0 is to be used in keyboards for applications such as text and data processing, general office environment, banking, point of sales (POS), telematic services, telephony apparatus, home electronic systems, numerical control of machinery and equipment, and input of personal identification number (PIN). The function zone ZN1 is to be used in keyboards for applications such as data entry, text and data processing, and general office environment.