usable storage

基本解釋

The storage and the usable amount of soil water resource vary with the situations of meteorology, irrigation and crop growing.
土壤水儲存量和土壤水可利用量隨氣象條件、灌溉以及作物狀況不斷變化；
The product is applied to transportation and storage of liquid nitrogen, liquid oxygen and other mediums. The adiabatic efficiency is excellent and the usable duration is long.
該系列産品用於液氨液氧等介質的運輸和貯存，産品絕熱性能好行用受命長。
www.bio-life.cn
The soil moisturegenerally is the state with low storage and low usability, all kinds of landremainds moisture potentiality in soil usable to the crops on the ground indifferent extent.
土壤水分一般処於低儲量、低利用的狀況，各地程度不同地保持著可供地麪作物利用的土壤水分潛力。採取調整辳林草的地區(qū)品種結搆；

In the 64GB model, I suppose I can accept 45GB of usable space, but seeing the available storage of the 32GB model halved is downright egregious.
FORBES: It's Time For Windows Tablet Manufacturers To Advertise Usable Storage Space
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