Names

In Fortran 90 variable names (and procedure names etc.)

• must start with a letter

     REAL :: a1 ! valid name
     REAL :: 1a ! not valid name

• may use only letters, digits and the underscore

     CHARACTER :: atoz ! valid name
     CHARACTER :: a-z  ! not valid name
     CHARACTER :: a_z  ! OK

• underscore should be used to separate words in long names

     CHARACTER(LEN=8) :: user_name ! valid name
     CHARACTER(LEN=8) :: username  ! different name

• may not be longer than 31 characters

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