A long time ago, my college professor defined a term which meant the number of source lines between a variable definition and its usage.
The lesson basically argued that the closer the two values are, the easier it will be to maintain over the long run.
My Google-Fu has been weak.
What is the term that describes this relationship?
I came across this concept for the first time whilst reading Code Complete 2.
I think the term you're looking for is 'span' in that book, which is explicitly the number of lines between references to a variable. In my interpretation, a variable declared and used on consecutive lines would have a span of 0.
The concept is reusable for other references to the variable too to give a wider measure of maintainability - the span between declaration and first use may be 0, but if the variable is then used again 100 lines later that's still pretty nasty.
Found on this page http://www.ppig.org/papers/11th-douce.pdf , on page 6 of the document it talks about Object Relation Measure, or ORM, and gives the definition and way to calculate it. I think this is what you might be looking for.
is it Code spatial complexity ?