They are referencing the amount of free SO2 levels in your wine. To do that properly you have to know the Ph of your wine and have an SO2 test kit. At the base level you should be sulfiting before bottling and/or while bulk aging. there are many factors though that impact how long your wine will last SO2, alcohol %, Tannins, quality of cork used, conditions of storage (temp/humidity)....and expectations. I have kept whites from kits over 2.5 years, reds to 4 years, I have some from my own concord vines from 2009 still in the bottle. I opened one of them last week it was still good (met my expectations!)