API call to get all SCR_Config key-value pairs

I'm having trouble tracking down how all the SCR_Config key-value pairs are set in test programs. I would like to be able to query all key-value pairs in each test program, and dump it to stdout for diagnostic purposes. I can already query the values if I know the keys, but I don't see a way to get the canonical list of keys known to SCR. The best I have found is a list in the documentation, but that may not be synced to the current state of the code. Is there a way to get all the currently-recognized keys?

Also, if I query a key from SCR_Config, but that key was never set in a config file or a previous SCR_Config call, will it return null or error, or some assumed default value? I'd like to see the default value.

Start by locating the SCR_Config implementation and the test programs that set configuration values, then compare their behavior with the documented key list. Done means providing a way to enumerate recognized key-value pairs for stdout diagnostics and documenting whether unset keys return defaults, null, or an error.