NEN EN 981 : 1997 + A1 2008

1 Scope
2 Normative references
3 Definitions
4 Ergonomic principles for the design and application of
    auditory and visual signals
    4.1 General
    4.2 Principles for distinctive characters
    4.3 Qualities of auditory signals
    4.4 Qualities of visual signals
5 System of auditory and visual signals
    5.1 Scheme of auditory and visual signals
    5.2 Scheme of auditory signal character
    5.3 Scheme of visual signal colours
6 Testing
Annex
ZA (informative) Clauses of this European Standard addressing
    essential requirements or other provisions of EU
    directives
Tables
1 Signals for general purposes, listed after degree of
    urgency
2 Character of signals for public alarm
3 Scheme for character of auditory signals
4 Scheme for colours of visual signals
2