Comments

It is good practise to use lots of comments, for example,

    PROGRAM Saddo
!
! Program to evaluate marriage potential
!
    LOGICAL :: TrainSpotter ! Do we spot trains?
    LOGICAL :: SmellySocks  ! Have we smelly socks?
    INTEGER :: i, j         ! Loop variables

• everything after the ! is a comment;
• the ! in a character context does not begin a comment, for example,

  PRINT*, "No chance of ever marrying!!!"

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