filetype Derived Type

    type, public :: filetype
!        integer :: FILE_NAME_LENGTH = 64
!        !< Length of string used for defining any filename
        integer ::      CONFIG_FILE_UNIT = 16
        !< Handler unit for config.md file
        integer ::        GRID_FILE_UNIT = 17
        !< Handler for input Gridfile; eg: grid_00.txt
        integer :: BOUNDARY_CONDITIONS_FILE_UNIT= 18
        !< Handler for Boundary condition file; eg: bc_00.md
        !integer, parameter :: STATE_FILE_UNIT = 10
        !< __Handler no longer in use__
        integer ::          IN_FILE_UNIT = 19
        !< Handler for restart file for block: eg: time_drectories/0001/process_00.dat
        integer ::         OUT_FILE_UNIT = 20
        !< Handler for output file for each block
        integer ::     RESNORM_FILE_UNIT = 21
        !< Handler for Residual output file. filename: time_directories/aux/resnorm
        integer ::      LAYOUT_FILE_UNIT = 31
        !< Handler for input multi-block layout and boundary condition file.
        integer ::    NODESURF_FILE_UNIT = 32
        !< Handler for storing node point on the wall
        !integer, parameter ::   WALL_DIST_FILE_UNIT = 33
        !< __Handler no longer in use__
        integer :: RES_CONTROL_FILE_UNIT = 34
        !< Handler for residual control file. filename: system/res_control.md
        !integer, parameter ::        INFO_FILE_UNIT = 35
        !< __Handler NO longer in user__; info is handled using print*, command
        integer ::     CONTROL_FILE_UNIT = 36
        !< Handler for input system/control.md file
        integer ::      SCHEME_FILE_UNIT = 37
        !< Handler for input system/fvscheme.md file
        integer ::        FLOW_FILE_UNIT = 38
        !< Handler for input system/flow.md  file
        integer ::     RESTART_FILE_UNIT = 39
        !< Handler for Restart file in Restart folder. eg: time_directories/0001/Restart/process_00
        integer ::       OUTIN_FILE_UNIT = 40
        !< Handler for file which controls what variables will be read or stored. system/output_control.md
        integer ::         MAP_FILE_UNIT = 41
        !< Handler for input multi-block mapping file with index and direction.
        integer ::    PERIODIC_FILE_UNIT = 42
        !< Handler for input periodic boundary condition file
        integer ::       STOP_FILE_UNIT   = 43
        !< Handler for Stop file
        !file names
        character(len=FILE_NAME_LENGTH) :: control_file="system/control.md"
        !< FILENAME string: Control file
        character(len=FILE_NAME_LENGTH) ::  scheme_file="system/fvscheme.md"
        !< FILENAME string: Scheme file
        character(len=FILE_NAME_LENGTH) ::    flow_file="system/flow.md"
        !< FILENAME string: FLow condition file
        character(len=FILE_NAME_LENGTH) ::   outin_file="system/output_control.md"
        !< FILENAME string: Ouput/Input variable control file
        character(len=FILE_NAME_LENGTH) :: layout_file='system/mesh/layout/layout.md'
        !< FILENAME string: Multiple layout/boundary condition file
        character(len=FILE_NAME_LENGTH) :: nodefile_temp="scratch.dat"
        !< FILENAME string: Temperory file for nodesurface points 
        character(len=FILE_NAME_LENGTH) :: surface_node_points='time_directories/aux/surfnode.dat'
        !< FILENAME string: Wall surface node points
        character(len=FILE_NAME_LENGTH) :: res_control_file='system/res_control.md'
        !< FILENAME string: Residual write control file
        character(len=FILE_NAME_LENGTH) :: resnorm_file='time_directories/aux/resnorm'
        !< FILENAME string: Residual output file
        character(len=FILE_NAME_LENGTH) :: stop_file='system/stopfile'
        !< FILENAME string: Halt/stop file
        character(len=FILE_NAME_LENGTH) :: mapfile='system/mesh/layout/mapping.txt'
        !< FILENAME string: Detailed multiblock mapping file with indicies and direction information at interface
        character(len=FILE_NAME_LENGTH) :: periodicfile='system/mesh/layout/periodic.txt'
        !< FILENAME string: Multiblock periodic boundary condition detials
        character(len=FILE_NAME_LENGTH) :: gridfile
        !< FILENAME string: Grid file
        character(len=FILE_NAME_LENGTH) :: bcfile
        !< FILENAME string: single block boundary condition detials
        character(len=FILE_NAME_LENGTH) :: outfile
        !< FILENAME string: single block solution output file
        character(len=FILE_NAME_LENGTH) :: infile
        !< FILENAME string: single block solution input file
        character(len=FILE_NAME_LENGTH) :: restartfile
        !< FILENAME string: single block restart file
    end type filetype