About timing precision of sdf file when simulation in ncsim

[iamyuchenjie]

Hello， every one.

I find my ncsim can only simualte the sdf file in precision of 10ps （round to 10ps）
For exampe，This is a simple BUF sdf information:

---

Code Verilog - [expand]
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(CELL
  (CELLTYPE "BUFCLKHD30X")
  (INSTANCE U10)
  (DELAY
    (ABSOLUTE
    (IOPATH A Z (0.263:0.266:0.266) (0.257:0.259:0.259))
    )
  )
)

---

But when I observe the timing sequence in simvision window. I found the simulator will round it to 270ps for example in when Z transfering from 0 to 1.
In my sdf file the Timescale (unit) is 1 ns. And in my testbench is 1ns/1ps. And according the tools documentation from cadence, the default timing precision of sdf elaberating/compiling is 1fs. I think that means we do not need to set any precision relating compiler option (like sdf_precision 1ps)in ma case. (BTW, I have tried such complier option, but still not wokr for my precision).

Anyone can teach me how can I watch/oberseve a delay of 266ps from my simulation window! Mnay thanks.!
My ncsim version is IES 2012, I thnik it was "latest" enough.

Many thanks.