日期：2011 年 12 月 2 日

The default of vim to read .f90 is fixed format, and vim will displays a yellow color when you am beyond 72 column. Then you can change it by use these command

:let fortran_free_source=1

or add the line below in ~/.vimrc

let fortran_free_source=1

from Re: VIM : used for Fortran files .f or .f90

you can also see

:help fortran.vim