at most evaluates as true if a statement is true for no more than some specified number of episodes.
For example, given the following case fragment,
05 Feb 03 06 Oct 03 07 Nov 03 HDL [2, 5.5] 7.3* 4.8 6.1* LDL 1.1 0.8 pending Trig 2.2 0.5*
at most 2 HDL are high
at most 1 LDL is not numeric
at most 1 Trig is not available
at most 3 Trig are high