silly question about Cufflinks gene_id column

[guil]

Hello all,

I've found some examples as below

Line retrieved form http://seqanswers.com/forums/archive...p/t-17351.html

chr3 Cufflinks transcript 1355 1401 1000 - . gene_id "CUFF.1"; transcript_id "CUFF.1.1"; FPKM "8019117703.6926527023"; frac "1.000000"; conf_lo "0.000000"; conf_hi "17278797233.473148"; cov "4041.635323";

Line retrieved form http://www.perlmonks.org/?displaytyp...ode_id=1020810

I Cufflinks exon 217157 217492 1000 - . gene_id "CUFF.55"; transcript_id "YAR060C"; exon_number "1"; FPKM "23.1145085280"; frac "0.302521"; conf_lo "11.245570"; conf_hi
"34.983447"; cov "19.544059";

well, can anyone tell me why sometimes there are the CUFF tag in both gene_id and transcript_id fields (red) and sometimes only in gene_id (blue)?? And why not in transcript_id?

tnks,
cheers,