Explanation:
 
This line can be summarised as "if the long range scan found a barrier or a mine, then go to one of the 'fragchk' routines"

There are different 'fragchk' routines which depend on Torque's current heading, and cloaking status. Each of them determines whether the enemy is directly behind the barrier or mine which was scanned. If it is, then it can be fragged.