If your sidescreens are fitted with glass then it must be safety glass that meets or is equivalent to the following standards
British Standard: BS857 or BS857/2 B55282 BSAU178
ECE Regulation 43 eg E11 43R·002439
EEC Directive 92/22 eg E11
Glass must bear one of the above Marks or show an equivalent standard.
Sidescreens must be securely fitted when on the vehicle, ie they can be detachable but when fitted and in use must be secured so as to not be able to fly off.