Meaning of UCSC annotation within one intron

[cam687]

Hi,

I am using the mm10 annotation from UCSC, downloaded for Homer ( http://homer.salk.edu/homer/data/genomes/mm10.v5.7.zip)

I'd like to understand what's the number after the parentheses (i.e. in this case, 2 and 3):

grep 'NM_001270494, intron 1 of 1).1'  mm10.full.annotation | wc -l
0

grep 'NM_001270494, intron 1 of 1).2'  mm10.full.annotation | wc -l
3

grep 'NM_001270494, intron 1 of 1).3'  mm10.full.annotation | wc -l
163

in the last example, the names are

intron (NM_001270494, intron 1 of 1).3--n

where n goes from 2 to 163, e.g.

intron (NM_001270494, intron 1 of 1).3--133

I've tried to do my research, but it's quite a difficult thing to describe it to google... Thanks in advance.