WHMIS symbols
Each WHMIS pictogram identifies one hazard class by its picture alone, and the SDS holds the safety detail no picture can fit.
A worked example
A container shows a black flame on a white diamond inside a red border, with no other markings. That picture alone means the contents are flammable, whatever the product name printed under it says.
The mistake people actually make
The pictogram identifies the hazard; the SDS is the separate document that gives the full detail, such as first aid steps and safe storage. Say "WHMIS", never "WHMIS 2015", and "SDS", never "MSDS" -- both are the current standard's own names, not the retired ones.