Official Description
6.9.3.1 On writing to a textfile, the values of TotalWidth and FracDigits are greater than equal to one; it is an error if either value is less than one.
Simplified Description
In other words, if you have
write(100:w)or
write(100.23:w:f)it is an error if w or f is less than one.
Error Handling
This error is reported if range checking is enabled.