What does the format nF10.8 mean?
It is a Fortran format specifier.

It means


$n$: repeat the input $n$ times, once for each weight
F: input is a floating-point number
10.8: the number is of total width 10 (including the decimal point), and has 8 digits to the right of the decimal point


This means the number cannot have more than one digit to the left of the decimal point, which makes sense since weights should all be $&lt; 1.0$.