Is there a method that will provide the name of the Mnemonic Space for the current device?

IO devices can be assigned to a mnemonic space using, for example:

u device::"^%X364"

Is there a method that will return the assigned mnemonic space for the current device?

I can infer it by attempting to write to the device using a non existent write /mnemonic and then inspecting the error returned, but this is rather messy and could potentially affect the status of the device.  For example:

USER>u 0::"^BAR"
USER>w /foo
<NOLINE>^BAR
USER 2d0>

Is there a method or system variable that will give me this information in a cleaner manner?

Thanks

George
www.georgejames.com