At the DESC meeting this summer (2016), Nicolas Regnault showed in the Photometric Corrections session that in order for LSST SNIa cosmology not to be systematics limited, the nominal "edge" of the filters, and the evolution thereof, needs to be known to and monitored at the 0.1nm level.
This is a somewhat surprising result (to some at least), and imposes some very stringent requirements on the photometric calibration system.
There is currently nothing in the SRD stating that we need knowledge of the filters at this level so this putative requirement is not being flowed down to the design in LDM-151.
This ticket is for someone to decide if a change to the requirements is necessary as this will likely involve making hardware change requests, given the current plans for filter and photometric calibration hardware.
A link to the slides can be found here: