A simple way to picture a multi-dimensional array might be:
$X[0,0,0] = Row, Col, Page
$X[0,0,0,0] = Row, Col, Page, Book
$X[0,0,0,0,0] = Row, Col, Page, Book, Shelf

and so on..

Since you are desining the code, the row/col association can be anything you like - whatever makes sense to you.
$X[0,0,0,0,0] = Shelf, Book, Page, Col, Row is NOT the SAME as above, but is equivelent, as long as you maintain the same references throughout your program.

Glenn
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Actually I am a Rocket Scientist! \:D