## Image Connection

Once a slot is reserved, it must be associated with an image. The following 4 routines connect an image to a specified image slot IS, in one of the 4 possible access modes (CReate, EXtend, REad only, Write and Read). No part of the image is immediately accessible after that, but the image slot is ready for memory connection using GDF_GEMS.

  SUBROUTINE GDF_CRIS (IS,GTYPE,NAME,FORM,SIZE,ERROR)

         GDF  CReate Image Slot
         Arguments:
              IS      I       Slot number                     Input
              GTYPE   C*(*)   Image type                      Input
              NAME    C*(*)   File name                       Input
              FORM    I       Image format (Real,Integer...)  Input
              SIZE    I       Image size                      Input
              ERROR   L       Error flag                      Output

  Creates a new file from the information available in image slot IS. The internal header should have been defined (through calls to GDF_WHSEC) before, and is written on the new file header.

  SUBROUTINE GDF_EXIS (IS,GTYPE,NAME,FORM,SIZE,ERROR)

         GDF  EXtend Image Slot
         Arguments:
              IS      I       Slot number                     Input
              GTYPE   C*(*)   Image type                      Input
              NAME    C*(*)   File name                       Input
              FORM    I       Image format (Real,Integer...)  Input
              SIZE    I       Image size                      Input
              ERROR   L       Error flag                      Output

  This routine is used to change the size of an image, usually by increasing the last dimension of the image. The new internal header must have been defined before in image slot IS, by use of the GDF_WHSEC routine.

  SUBROUTINE GDF_REIS (IS,GTYPE,NAME,FORM,SIZE,ERROR)

         GDF  REad Image Slot
         Arguments:
              IS      I       Slot number                     Input
              GTYPE   C*(*)   Image type                      Output
              NAME    C*(*)   File name                       Input
              FORM    I       Image format (Real,Integer...)  Output
              SIZE    I       Image size                      Output
              ERROR   L       Error flag                      Output

  This routine is used to open an existing image for ReadOnly operations. The image is available for file sharing.
  SUBROUTINE GDF_WRIS (IS,GTYPE,NAME,FORM,SIZE,ERROR)

         GDF  WRite Image Slot
         Arguments:
              IS      I       Slot number                     Input
              GTYPE   C*(*)   Image type                      Output
              NAME    C*(*)   File name                       Input
              FORM    I       Image format (Real,Integer...)  Output
              SIZE    I       Image size                      Output
              ERROR   L       Error flag                      Output

  This routine is used to open an existing image for ReadWrite operations. The image is not available for file sharing.