Google Waves have an ID, and a URL. This information is needed with some add-ons, and of course is needed in order to tell someone how to find your Wave.
Yet Google does not make it obvious what the URL and the ID of Waves are. Here's how to tell...
First, the URL. The URL of a Wave is visible in the address bar of the web browser when you have a Wave selected. For example, this is the Elgintime vintage watch Wave:
The Wave ID is included in this path. It is:
To get this, the escaped "%24" has been changed to "+".
Sometimes, and I don't know why, a decimal point and a number appear at the end of the URL, like this: