Omron ZX-L-N Manual page 18

2. AEL: Accessible Emission Limit
The maximum accessible emission level permitted within a particular class.
For your reference, see ANSI Z136.1-1993, Section 2.
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Figure A Warning label - Hazard symbol
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Figure B Explanatory label
ZX Series (ZX-L-N)
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Smart Sensors (Laser Type)