second most recent picks the second most recent non-blank value. For example, given the following case fragment,

           01 Jun 03    20 Jun 03    30 Jun 03    15 Oct 03    02 Nov 03
HDL           2.0          2.1          2.2          2.4          pending
LDL                        4.5          4.7                       3.1
Trig          3.2                                    3.6
LipidDrug     N                         Y            /

second most recent HDL is 2.4

second most recent LDL is 4.7

second most recent Trig is 3.2