2405 polarity of diaphragm?

[Flodstroem]

Hi
Need a guidance here from someone that is familiar with 2405ś
Im trying to install the D16R2405 in the driver. But was unsure of the polarity. The dia has a black!!?? mark/dot at one of the thin copper (solder) leads?
Is this a mark for connection to the pos or neg terminal?

[JeffW]

Negative.