6.6.6.3 For round(x), if x is positive or zero then round(x) is equivalent to trunc(x+0.5), otherwise round(x) is equivalent to trunc(x-0.5). It is an error if such a value does not exist.
In other words, it is an error to use the round function to convert a value of real type into a value of integral type, if the real value is outside the range of integral values supported by Irie Pascal. For example
round(1.0e16)
is an error.
This error is never reported.