The Service Set Indentifier (SSID) is a unique identifier that wireless networking devices use to establish and maintain wireless connectivity. Multiple Access Points (APs) on a network or sub-network can use the same SSIDs. SSIDs are case sensitive and can contain up to 32 alphanumeric characters. Do not include spaces in your SSIDs.
You can configure up to 16 SSIDs on an 1200 series AP and assign different configuration settings to each SSID. All the SSIDs are active at the same time. In other words, client devices can associate to the AP using any of the SSIDs. For more information, refer to the Configuring Multiple SSIDs section of the document.
For additional information, refer to these documents: