Even definition of base weight varies. My definition of base weight is key big items:pack, shelter, sleep bag and pad. I suppose my reason behind it is due to fact those are generally biggest items in term of volume and/or weight. I divide the rest into two categories: need and want. Lol. Ah, well.
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It is one of the blessings of wilderness life that it shows us how few things we need in order to be perfectly happy.-- Horace Kephart