< evaluates as True if the left hand value is less than the right hand value.
Similarly, > evaluates as True if the left hand value is greater than the right hand value.
Similarly for <= (less than or equal to) and >= (greater than or equal to).
These functions are only used to compare numeric values, not text values.
For example, given the following case fragment,
Cholesterol 7.3 5.6 6.1 Triglyceride 1.1 0.8 1.2
Cholesterol < 6.5
Cholesterol <= 6.1
Triglyceride > 1.1
Triglyceride >= 1.2
Triglyceride < Cholesterol