Rockets - M70B vs M70B Zonar M70

[PhantomHans]

What are the Zonar M70 variant of the HEAT rockets used for?

Obviously the HEAT warheads are better for tanks, the HE-Frag for soft stuff, but the only reference I can find to Zonar seems to be that it's a proximity fuse.  So why is it on a HEAT warhead rocket?  Is this to get the correct standoff for the charge to form and penetrate better or am I misunderstanding the Viggen weapons?

[PhantomHans]

@Zabuzard Wonder if you can enlighten me on these?  I watched some tutorials and read the guide .pdf but still have no answer.