Some Online Information Systems send a flag with each sample in the case (in addition to the sample value, upper and lower reference range values and units). The syntax … flag is used to get access to these flags. Note that at the time of writing, these flags are not actually shown in the case in any way.
In a typical scenario, the flags in question are integers between -3 and +3 and represent degrees of abnormality. In such a situation we can define the “abnormals” from a list of group attributes, as follows
{electrolytes, lipids} for which at least 2 absolute value of $x flag > 2