The Offset reference article from the English Wikipedia on 24-Apr-2004
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Offset

Helping orphans the way you would do it
In computer science, an offset within an array or other data structure object is an integer indicating the 'distance' from the beginning of the object to a given element or point, presumably in the same object. The concept of a distance is only valid if all elements of the object are the same size.

Example

Given an array of characters A containing "abcdef", one can say that the element containing the letter 'c' has an offset of 3 from the start of A.