Superseding the EN 1838:1999, the 2013 edition of the European standard has the status of national standard and came to action in January 2014. It specifies  the  luminous  requirements  for  emergency  escape  lighting  and  standby lighting systems in premises where such systems are required. There are references in BS 5266-1: 2016 and Lighting Guide 07 pointing to this guide.

Emergency lighting is provided when the supply to the normal lighting fails and is therefore powered from a source independent of that supplying the normal lighting.

This document recognises two main  types of emergency lighting - escape lighting and standby lighting.

Emergency lighting BS EN 1838-1

More detail.

Escape Lighting

Safety Signs