From APACS online help:
In 4-mation, input variables, output variables, and variables communicated from another ACM have an attribute called "quality". Quality indicates the validity or certainty of a data value. There are four possible data quality values:
The quality is revealed by color and delimiter. The display for each of these quality attributes is shown in the list below.
QUALITY DISPLAY COLOR DELIMITER
GOOD CYAN (LIGHT BLUE) NONE
QUESTIONABLE YELLOW Q
UNAVAILABLE YELLOW U
BAD RED B
If a value has bad quality, an error message is displayed instead of the bad data value.
Example: If a type is not stated when a function block needs to be typed (ANY type output is not wired to a typed input or variable) the ANY type output displays "B Tag not found" in red.
If any quality other than GOOD is displayed, the problem should be investigated. For example, if an input channel is reporting a value with a quality other than GOOD, the field transmitter may have failed.