Omron CJ2 User Manual page 22

Symbols
The triangle symbol indicates precautions (including warnings).
The specific operation is shown in the triangle and explained in
text. This example indicates a precaution for electric shock.
The circle and slash symbol indicates operations that you must
not do. The specific operation is shown in the circle and
explained in text. This example indicates "do not disassemble."
The filled circle symbol indicates operations that you must do.
The specific operation is shown in the circle and explained in
text. This example shows a general precaution for something
that you must do.
The triangle symbol indicates precautions (including warnings).
The specific operation is shown in the triangle and explained in
text. This example indicates a general precaution.
The triangle symbol indicates precautions (including warnings).
The specific operation is shown in the triangle and explained in
text. This example indicates a precaution for hot surfaces.
16 CJ2 CPU Unit Hardware User's Manual