The particular measurement categories at escape signs for emergency operation according to EN 1838 for backlit safety signs (escape sign luminaires) are:
luminance of the backlit safety sign in emergency and mains power operation
minimum, average and maximum luminance of the area with the green safety colour
minimum, average and maximum luminance of the area with the white contrast colour
average luminance of the entire safety sign
For illuminated safety signs (escape signs), the minimum illuminance must be measured on the surface of the illuminated safety signs.