Simple Vector Notation

Homework Statement

Does
$$r_{12}$$
mean distance from point 1 to point 2, or point 2 to point 1?

The Attempt at a Solution

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Where you typically see this notation is the vector form of Coulomb's law where electric force exerted by a charge q1 on a second charge q2 is written F12

Cheers, I'm using in it Biot-Savat law so same thing really. I always forget it, it drives me nuts! Thanks again.