You can initialize a Linux partition, or alternately you can mount a previously initialized one.
"Debian GNU/Linux: Guide to Installation and Usage"
John Goerzen and Ossama Othman
Moreover, you must initialize any partitions that you created in the disk partitioning step.
"Debian GNU/Linux: Guide to Installation and Usage"
John Goerzen and Ossama Othman
You can use the arrow keys to select the menu items to initialize or to mount disk partitions if you have any more partitions to set up.
"Debian GNU/Linux: Guide to Installation and Usage"
John Goerzen and Ossama Othman