Meaning of -1 for scene boundary label

[JonghwanMun]

In the first 10 lines at the label file of tt0047396.txt, there is -1.
I think both 1 and -1 mean boundary.
So, I wonder why do you use -1 and what is the difference between 1 and -1?

0000 0
0001 0
0002 0
0003 1
0004 -1
0005 -1
0006 0
0007 1
0008 0
0009 1

[SnoopyMark]

I have the same question with you. BTW, do you figure it out?

[nithya3]

I have the same question. Did anyone figure this out? Does it mean unsure scene changes by any chance?