PyroGenesis Canada Inc (PYRGF)

[MasonM]

Tom - I would expect that the -45 is the low-end tolerance, and the +15 is the high-end tolerance. Meaning, it is more acceptable to have particles a bit smaller than the target size than it is to have them a bit larger. The standard notation that you are accustomed to assumes that the high and low end tolerances are the same, which isnt always the case. The target is still placed where it is because that is the desired size. I wouldnt be surprised if the true spec were a gradation spec, listing an allowable percentage for each size of particle. Specs like these are used in sand and gravel fill for road and other construction projects. Hope that helps. I could also be wrong, but that is my guess.