I am using fasterq-dump to download from sra, and using split-files to split paired end reads. as a result i receive one or two files. when i have two files they are in the format *_1.fastq, and another file *_2.fastq or *_3.fastq or *_4.fastq I cannot find what is the meaning of these numbers?
the command I am using: fasterq-dump --split-files -O /media/lab/fastq ERR016705
for example: ERR016705 has 2 files: _1, _4 ERR015587 has 2 files: _1, _2