The revised code of practice came into printed circulation on the 17th May 2017. Copies are available at Chimera climbing wall, as well as Bowles Rocks and Harrison's Rocks. If you are unable to get hold of a printed copy you can download a copy here: BMC Southern Sandstone Code Of Practice.

The code of practice is all about protecting the rock. 

As the rock is so soft, it is essential the preserve the thin outer layer and to reduce erosion as much as possible. Moving ropes cut into the rock, so please set-up your ropes correctly.

Key points are:

Top-rope, bouldering or solo climbing only.
Use a non-stretch (static) rope and slings for top-rope setup.
Make sure the karabiner hangs over the edge of the crag and moving ropes do not 
        come into contact with the rock.
Clean shoes before each climb - bring a piece of carpet to wipe your feet, to avoid 
        rock erosion and make it easier to climb.
Walk off when you have finished a climb, do not lower off or abseil.
Keep chalk use to a minimum.
Avoid climbing on wet rock. - It can cause irreversible damage. 
Use of harsh boulder brushes and toothbrushes are strictly forbidden.

The sandstone is fragile beneath a harder, weathered outer layer which protects the soft rock beneath and takes many years to reform if damaged.