undefined symbol G0025:"_pdate"

这是在运行下载的Hansen(1999) threshold model代码时出现的报错,请问如何解决.多谢!
相关代码如下
_pdate="";
ylabel("Likelihood Ratio");
title(titname);
xlabel(xname);
xy(qq,lr~(ones(rows(qq),1)*cc));
endif;
output on;
if maxc(r) .ne 0;
"Fixed Thresholds " rr';
rrr = sortc((rr|rhat),1);
else;
rrr = rhat;
endif;
"Threshold Estimate " rhat;
"Confidence Region " minc(rhats)~maxc(rhats);
"Sum of Squared Errors" sse1;
"Trimming Percentage " _trim;
"";"";
我不懂GAUSS,还想问.最后这个"";"";是什么意思.多谢多谢