This document defines a measure for the spectral quality of LED luminaires in terms of the ratio of the amount of visual light emitted by the luminaire versus the amount effective for charging photoluminescent products contained in that spectrum. Fulfilment of this document by a LED luminaire will ensure general compatibility of the luminaire with photoluminescent marking systems. This document alone does not provide any means of compliance to fulfil any airworthiness requirements. For a specific aircraft installation, the spectral power distribution and illuminance at the photoluminescent marking systems are relevant.