Test equipment banana socket spacing - Standard?

[dohzer]

I've purchased some male BNC to dual banana socket adaptors like these:
https://en.wikipedia.org/wiki/File:Binding_post_adapter.JPG

I've also purchased some reverse gender ones (male banana plug to female BNC), but I can't seem to see if the physical pin spacing/separation on equipment (multimeters, lab supplies, etc) is standard.
Measuring my Rigol DP832 Power Supply, the positive and negative binding posts appear ~20mm appart, and my no-name DMM looks around 19mm.

Is there a standard? Does anyone have equipment that varies greatly from the above?

 

[hexreader]

As far as I can see, 19mm is the standard. I have no evidence to back this up, other than looking at twin 4mm socket specifications.

Having used vernier calipers to check adapters like the one you link to, and real PSUs, test equipment, etc, the real-life spacing varies between 18 mm and 20mm.

It seems that any adapters are required to be a little bit flexible to accommodate the real world.

Maybe someone else has some documentary source that can be trusted. I do not.