This command compares two expressions. Notice that when you want to check for values being bigger or smaller, the comparison arg1>arg2 is made. If this evaluates to true, the $_BS_FLAG is set to 1, meaning the value is bigger. So you test if arg1 is bigger/smaller than arg2.
arg1 First expression to compare.
arg2 Second expression to compare.
This command sets the internal variables $_EZ_FLAG and $_BS_FLAG. They are checked when a branch is performed.