# How does vtkTimeStamp::GetMTime() work?

**URL:** https://discourse.vtk.org/t/how-does-vtktimestamp-getmtime-work/10909
**Category:** Support
**Created:** [March 7, 2023, 2:23pm UTC](https://discourse.vtk.org/t/how-does-vtktimestamp-getmtime-work/10909 "2023-03-07T14:23:28Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![mau\_igna\_06](https://discourse.vtk.org/user_avatar/discourse.vtk.org/mau_igna_06/32/8064_2.png) [@mau\_igna\_06](https://discourse.vtk.org/u/mau_igna_06)
#### Post date: [March 7, 2023, 2:23pm UTC](https://discourse.vtk.org/t/how-does-vtktimestamp-getmtime-work/10909/1 "2023-03-07T14:23:28Z")

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Here is my test code:

```auto
from time import sleep
t = vtk.vtkTimeStamp()
t.Modified()
print(t.GetMTime())
sleep(3) # so next time should be 3 seconds later
t.Modified()
print(t.GetMTime())

```

It outputs:

```auto
255513
255514

```

So why `255514 - 255513` is different than `3` (i.e. the sleep time) ?

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<div class="post-metadata">

### Author: ![will.schroeder](https://discourse.vtk.org/user_avatar/discourse.vtk.org/will.schroeder/32/233_2.png) [@will.schroeder](https://discourse.vtk.org/u/will.schroeder)
#### Post date: [March 7, 2023, 2:34pm UTC](https://discourse.vtk.org/t/how-does-vtktimestamp-getmtime-work/10909/2 "2023-03-07T14:34:47Z")

</div>

MTime is not based on clock time, it is based on a monotonically increasing large integer.