Why is it called Alliance?

In previous post, it is mentioned that ZigBee is an alliance. In this post, I will try to explain why it is called Alliance.

It is known that ZigBee uses IEEE standards as a base. Also, it has been established by many companies and support of some organizations. ZigBee alliance membership does not have any specific rules which means anyone can join. The other important aspect of ZigBee is interoperability which improves cooperation between companies. In addition, confidentiality is an important factor. Only members can access to the ZigBee standard. When standard becomes well known, membership of IEEE gives reliance. In addition, small companies actively involved because Zigbee aims cheap final products and they don't want to involve in long time consuming process.