Proc expand: Skip the most recent obs

[ZZB]

proc expand data=XXX out=XXX method=none;
by AAA;
convert high = high1 / transformin=(movmax 12 trimleft 10);
run;

I want to get the Maxmium obs from the most recent 12 obs in the moving windows. But I want to skip the most recent 1 observation. In fact I use 1-11st obs, while skipping 12st obs. How to code it?

[PGStats]

Try

proc expand data=XXX out=XXX method=none;
by AAA;
convert high = high1 / transformin=(movmax 11 lag 1 trimleft 10);
run;