Omen

兆 is a picture of the fractures themselves — the paired splits raised in a heated scapula or plastron, which 卜 records the making of. From the crack came the reading: 兆 is the portent, the thing about to happen made visible slightly before it happens, which is as close as any script comes to a word for the future tense of an event. Then it left divination entirely and became a number. In classical reckoning 兆 is a million million; in modern technical compounds it does duty as mega-, so 兆字節 is a megabyte and the same character means two quantities six orders of magnitude apart depending on the sentence. A mark nobody drew on purpose, which became the future, and now measures storage.