nordpredv包中，cuttrend参数是什么意思，

Different cut trend scenarios, using average drift (recent = FALSE):

plot(nordpred.prediction(est, startuseage = 6, cuttrend = c(0, 0, 0, 0, 0), recent = FALSE),
standpop = wstand, new = TRUE)
plot(nordpred.prediction(est, startuseage = 6, cuttrend = c(1, 1, 1, 1, 1), recent = FALSE),
standpop = wstand, new = FALSE, lty = c(1, 2))
plot(nordpred.prediction(est, startuseage = 6, cuttrend = c(0, .25, .5, .75, .75),
recent = FALSE), standpop = wstand, new = FALSE, lty = c(1, 4))
生成出来的的图是什么意思， cuttrend = c(0, 0, 0, 0, 0)， cuttrend = c(1, 1, 1, 1, 1)都是什么意思，求帮忙，谢谢