VTH changes in DC from Hspice

Hello, everyone.

I’d like to know the threshold of the MOS transistor. And I found the “.print vth()” or “.print lv9()” can give the threshold voltage. 
But 
1) What does the output value of the .print lv9(Mxx) mean? Is it the same as the VTH0 in the lib?
2) why does the threshold voltage changes in a .DC sweep? when VIN sweep from 0 to 1v, the threshold of NMOS changes from 241.6751m to 421.5062m, for PMOS: from 360.5821m to 140.6713m.

3) the run.lis file gives the threshold from the mos.lib is VTH0p = -0.365, VTH0n = 0.423

Thanks in advance!


The script is:

*.lib './mos.lib' tt
.lib './PTM_bulk_65nm.lib' tt
.global VDD GND
.options list post
.temp 25

MMN OUT IN gnd gnd nmos l=60n w=266n m=1
MMP OUT IN vdd vdd pmos l=60n w=134n m=1

VIN In GND 1v
VVDD VDD GND 1v
VGND GND GND 0v

.DC vin 0v 1v 0.01v

.MEASURE DC VTH WHEN V (IN) = V (OUT) 
.MEASURE DC VTGAIN DERIVATIVE V (OUT) AT VTH
.print vth(MMP) vth(MMN)
.print lv9(MMP) lv9(MMN)

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