PS: what was the point to use D65 filter with Spectrolino to measure the target for him ?
Many industrial measurements standardize on D65 and the 10 degree observer. While you can compute this using reflectance data, you won't get quite the same results when there is fluorescence present, whereas the D65 filter will gives a more accurate result.
[ Interestingly one of my Spectrolino's came with a UV filter. I guess it was an option, since it isn't mentioned in the manual, nor did one come with the other Spectrolino I was given. ]