Probably the most common reason for using composite keys is for backwards-compatibility.

使用组合键的最常见的原因或许就是为了向后兼容。

youdao

The reason for this arrangement: backwards compatibility.

这样安排的原因是：向后兼容。

youdao

I know the extra two characters are annoying; I know this will break backwards compatibility.

我知道这两个额外的符号十分讨厌；我也知道这将会破坏向后兼容性。

youdao

Today's Sony PS3 unveiling has opened up a world of questions regarding how Microsoft expects to maintain a competitive edge against a system that will supposedly have more than double the raw processing power, a next-gen media drive (Blu-ray, in this case), two-generation backwards compatibility, and even support for 1080p hi-def.

ENGADGET: & Joystiq's live coverage of Microsoft's Xbox 360 E3 event

Like other NETGEAR 802.11ac WiFi Routers, its compatibility with next-generation WiFi devices and backwards compatibility with current WiFi devices provides a future-proof solution.

ENGADGET: Netgear D6300 mates 802.11ac WiFi with ADSL, risks one heck of a mismatch

We've got to say, the dual-backwards compatibility is pretty sweet.

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