Considering the 5 modes of operation of wireless access points described on this page, there a among them:
Mode 2 - Bridge. Most APs can also be configured as a Bridge. In such Configuration the AP can only communicate with another AP that is configured as a Bridge. This mode is useful to Bridge two LAN segments that are apart, and it is preferred to connect them wirelessly. Plug one AP Bridge to a Switch on the first LAN, the other AP to a Switch on the second LAN, and they are connected.
Mode 3 - Client. Few APs can also be configured as Clients. In such a configuration they act as a "Fancy" regular Wireless card that usually goes on a computer. Under such configuration The AP can only communicate with Wireless Cable/DSL Router or an AP configured as a Gateway.
Mode 5 - Independent Bridges. These are units that are actually Wireless clients Independent of Drivers (Driverless Wireless Client Cards). As a result they can be connected to a device that supports Wireless but it is not a regular computer. They can turn Ethernet equipped like Printers and Game Boxes into Wireless compatible devices. (Linksys WET11, D-Link DWL-810). Plug one of these into a Switch and you can connect few computers with wires to the switch while these computers are Bridged Wirelessly to the main Network.
When searching for "Client Mode" in the context of APs the information seems unclear. Most times it is described more like "Mode 5" which means it can connect wirelessly to another AP in "Gateway" or "Bridge" mode and on the other end has a wired (Ethernet) connection which can be connected to a single computer or switch. But then what exactly do they mean by "Mode 3"?
So what I'm looking for is an even more precise definition of the operation modes if there is one. In particular I would like to know if there really is a formal definition of the Modes 3 and 5 or if it is rather the type and configuration of a given device that makes a difference.