i know that some rather most of the jingos would now tell me that if this happens then india will surely retaliate with a similar but more massive response. i disagree! Why?
Well when the CS is based of the fact that it should culminate well before the enemy react in terms of a counter-value strategic nuclear attack i.e. it leads to a nuclear war this ensuring MAD, which in turn means that CS is nuke allergic, then pray tell me why would india NOT stop the assault and wind up the CS knowing full well that it can now not achieve the stipulated targets, instead of going all gung ho and retaliating to a tac nuke attack with a strategic one? Idiocity, perhaps? Or is it that your commanders would forget that the basis of CSD was nuke phobic?
Now this brings me to your other query. IS Shaheen and Nasr comparable? Well for now (keeping in view your limited understanding) i'll only say that targeting an IBG with Shaheen would mean inviting india to respond in kind as the this launch might not restrict itself to a counter-force target but it's sheer magnitude would make it a counter-value one. Also,the close proximity of the attacker and the defender would rule out a ballistic missile attack, why? Coz it's stupid. Moreover, this will never happen because if Pakistan finally decide to go nuclear, well it would choose target that fir in the counter-value/force pretext. Now compare this with Nasr, a 60 km range missile, with a very lower yield that would target a small portion of the the attacking force, which even if wiped off, might not result into a similar response, one because you dont possess a similar weapon, two raising the bar and retaliating with a strategic strike would make india the culprit, three if common sense if applied, a tac nuke attack is responded with a tac nuke attack, not with a strategic one!
Savvy?