use of seq_id. was: [Bioperl-l] Bio::Tools::GFF use of seqname

[Dave Howorth]

Hilmar Lapp wrote:
> Actually, $feat->can('seq_id') must be true at all times iff 
> $feat->isa("Bio::SeqFeatureI"), so it's kind of superfluous to test for it.

Where does this come from, please?  In the SeqFeatureI documentation it 
says seq_id 'is an attribute such that you *can* store the ID' (my 
emphasis).  You seem to be saying that if I'm creating a bunch of (sub) 
features just so I can use Bio::Graphics, I must attach a seq_id to each 
and every one.

I have an inverse question that I haven't managed to find an answer to 
yet. If I'm displaying these sub-features as segments, how can I attach 
some text to the feature that will be displayed alongside each 
individual segment?

Thanks, Dave