In the Details-->Instrument Choice section of the SAS 9.2 documentation for PROC PANEL, the information on how the MAXBAND option works in the procedure is incorrect. The correct information is the following:

If the MAXBAND option is specified, then the following is true under any selection criterion (let t be the time subscript for the current observation). The first observation for the endogenous variable(as instrument) is max(t-MAXBAND, 1) and the last instrument is t-2. The first observation for a predetermined variable is max(t-MAXBAND, 1) and the last observation is t-1. The first and last observation for an exogenous variable is given in the list below.

Trailing: If t < MAXBAND, then the first instrument is for the first time period and the last observation is MAXBAND. Otherwise, if t >= MAXBAND, then the first observation is t-MAXBAND+1, while the last instrument to enter is t .

Centered: If t <= MAXBAND/2, then the first observation is the first time period and the last observation is MAXBAND. If t > T-MAXBAND/2, then the first instrument included is T-MAXBAND+1 and the last observation is T. If MAXBAND/2 < t <= T-MAXBAND/2, then the first included instrument is t-MAXBAND/2+1 and the last observation is t+MAXBAND/2. If the MAXBAND value is an odd number, the procedure decrements by one.

Leading: If t > T-MAXBAND, then the first instrument corresponds to time period T-MAXBAND+1, while the last observation is T. Otherwise, if t <= T- MAXBAND, then the first observation is t and the last observation is t+MAXBAND-1.