Question about the parameter -fs in bedtools.

Question

[Spencer]

Hi, i have recently learned Bedtools,but i'm not totally understand the parameter -fs. For example,in the chip-exo pipeline in order to generate stranded read counts trim 1,using -fs. Code as following: bedtools genomecov -ibam bamfile -fs 1 -d -strand + bedtools genomecov -ibam bamfile -fs 1 -d -strand - So what exactly does it do?

Thanks.