Noncode transcripts with strand information as .

Question

[yasokannan93]

Hi,

I am trying to work with annotations from noncode and have downloaded the http://www.noncode.org/datadownload/NONCODEv5_human_hg38_lncRNA.gtf.gz gtf file. While processing the file, I noticed some of the transcripts have . (dot) as strand. I was wondering why this is occurring. eg:

NONHSAT256431.1

NONHSAT257827.1

NONHSAT252000.1

Thanks in advance for the help.