Matrix notation with four subscripts - what does it mean?

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For the first time I've stumbled upon following notation:

$$ \Delta X_{ji} / X_{ijji}$$

It is described as "given the percentage reduction in total inputs"

Context: paper in economics. Describes manipulations for matrices that describe economic activitiy (e.g. in which sector i supplies a certain amount of goods to sector j).

Appreciate any help. I would guess it means

$$ \Delta X_{ji} / X_{ij} X_{ji}$$ but can someone verify?