<Li> With land; moats, trenches or entire buildings may be involved . </Li> <Li> With buildings or certain forms of transport, turrets may be involved . </Li> <Li> With information; encryption, steganography or self - destruct capability may be involved . </Li> <Li> With communications reliability, channel - hopping may be involved, as immunity or attempt thereat from jamming . </Li>

..is a property that describes various characteristics of an entity