What does Von Duprin mean by OP?

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This option is not available as there is no NL cam to directly drive the rods and using a key to lift the heavy stainless, brass or bronze rods would damage the key. 
No, the 98/99 series mortise exit device should be ordered as NL less trim. IE, 9875NL-L/TRIM. NL-OP suffix is normally used with the 98/99 series rim, surface and concealed vertical rod devices wh...
Chexit devices shipped with motor after 8-24-2015. 1. When Chexit device is set for more than zero second rearm time (factory setting is 10 second rearm time) and device goes into alarm immediatel...
Chexit devices shipped with solenoid prior to 8-24-2015. 1.  When Chexit device  is set for more than zero second rearm time (factory setting is 10 second rearm time) and device goes...
The 388 Cylinder Control is required for the NL-OP function on a 33A/35A series exit devices. The 110NL is used on 22 and 98/99 series exit devices not 33/35A series devices.
This is possible: For metal doors prep door according to the 24R/V NL-OP Template or the 25R/V NL-OP Template and for wood doors use 24R/V NL-OP Wood Template or 25R/V...
The NL-OP function for 25-C uses the 718C trim, so template T-2211 for metal doors and W-2211 for wood doors for 718 trims prior to 2/28/2011. T-2211 for trims prior to 2/28/2011 W-2211 for...