[Boatanchors] somewhat off topic (switch ID)

[Dick KF4NS]

This one has me scratching my head. In the Mouser catalog are some 
rocker switches I am looking at but not sure of the identity. They are 
all DPDT.

Here are the contact forms they list:

(ON)-OFF-(ON)  this one I understand, it is momentary for the status 
in ( )

ON-NONE-ON

ON-OFF-ON

What is the difference in the last two? They are different listed part 
numbers for the same type switch.

73, Dick KF4NS
St Petersburg, FL 33714 USA
Keep The Glow!