The actions that are initiated by pressing the five-way navigation button may vary significantly
based on (1) the user’s location within the menu structure, and on (2) a particular action item of
interest (of many) on one individual screen. Focus refers to a way of identifying that single item
(from possibly several items) on the LCD screen.
大致意思：操作仪器要通过一个五向按钮，但因为两个原因使操作有所不同（1）是用户所在当前菜单位置，这个（2）就让我头大，不知他想说什么。最后那句是说当前项就是那个在屏幕上明显与其他选项区分开的的选项。
这是个美国公司的产品说明手册，希望内力深厚的各位帮个忙！给些专业意见。
谢谢！！
问题补充：Focus refers to a way of identifying that single item
(from possibly several items) on the LCD screen.
在这句的理解上看来我们有分歧。
The actions that are initiated by pressing the five-way navigation button may vary significantly
based on (1) the user’s location within the menu structure, and on (2) a particular action item of
interest (of many) on one individual screen. Focus refers to a way of identifying that single item (from possibly several items) on the LCD screen.
通过触按五向导航钮来启动的动作根据下列情况而有所不同：
（1）是用户所在当前菜单位置；
（2）在个人屏幕上对其中感兴趣的特殊项目进行点击；
（屏幕上有很多项目可点击)
关键是在LCD屏上对某个单项的识别（可能从多项中选择）。
我推测一下第二点的意思。
（2）显示屏上某个你感兴趣的选项。 重点是把这个屏幕上的选项与其它可能选项区别开来的方法。
最后一句可能和上下文有关联。
