fsl software package provides transitional dummy package, you can install in your Debian 8 (Jessie) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install fsl
fsl is installed in your system.
Make ensure the fsl package were installed using the commands given below,
$ sudo dpkg-query -l | grep fsl *
You will get with fsl package name, version, architecture and description in a table
| Distro | Debian 8 jessie |
| Section | Science |
| Package | fsl |
| Version | 5.0.7-4 |
| Description | transitional dummy package |
| Sub Section | Science |