Slitherine

Page 33, right-hand column, regarding flank and rear attacks says:
"A move that satisfies all of the above is considered to have assaulted the flank or rear of the enemy unit. IF THERE IS NO OTHER FIRING THAT COULD STOP THE ASSAULT COMPLETING, the unit being assaulted drops a level of cohesion BEFORE it can fire defensively at other assaulting units, otherwise it drops a level of cohesion AFTER it has fired any defensive fire..." (capitalized italics for my emphasis, non-italicized caps were left as in the actual text)

What is the "other firing" that could stop the assault? Only assaulted units can fire during the assault phase (possibly assisted by other units if the assaulting unit is in the supporting fire zone). Does the "other firing" refer to these flanking supporting fire units? I wouldn't think so as they only add a die to the fire of the assaulted unit, rather than firing separately (and a unit assaulted in the flank or rear cannot fire at the flank/rear assaulting unit). I can only conceive that the "other firing" refers to the case in which the assaulting unit actually contacts or assaults more than one unit, as only assaulted units can fire.

Is there some other meaning?
I've seen a reference to "opportunity fire" in these discussions but have found no rule which allows it.
I suspect this question has been asked before and I've simply missed seeing it here.

Any unit can fire at the assaulters if the assaulters pass within arc and within 2mu of them in the charge. They would be the "other" fire.

Could you direct me to the rule on that?

p. 32, Defensive Fire:

(second paragraph)...only fire allowed is at assaulting units at close range...so, anything that assaults, as it moves, everything it moves to within 2MU of may shoot at it

except that the original target of an assault does not fire ion that assault is intercepted.

nor anyone intercept or counter charging.

That wording from p. 32 seems a rather light peg from which to hang such a heavy principle...and the examples only show the supporting fire...but if that's the basis and interpretation, ok.

intercepting and taking defensive fire are two different things. An intercept would be declared before the chargers move and any defensive fire takes place. If the intercept is successful the charge is cancelled no effect or tests on the original target.

Defensive fire is from any unit the chargers pass within 2 MU of and there is no intercept. So if you go to charge into the rear of an enemy and take shooting before you get there from some other enemy unit and get stopped without making contact there is no flank or rear charge. Unless I would imagine you passed your CMT to close and were able to make it into contact still.