simSV bed output explanation of DEL and INS position

[charliechen912ilovbash]

Hi,
I am using simsv and got the bed output.
But I am a little confused about the position in bed file, especially for DEL and INS.
For example,
chr1 10 100 DEL
I guess this coordinate is the input ref.fa of simsv ?

But for INS,
chr1 10 100 INS
Is this coordinate the simulated.fasta ?