[DAS2] feature filter examples

[Andrew Dalke]

I'm having some difficulty understanding the feature query
language.  There's an example in the spec which is

     overlaps=Chr3/1000:2000;type=exon,intron,splice_site

     (Features of type exon, intron, or splice_site that
     overlap region 1000-2000 on Chr3.)

Based on that, the following appears to be legal

   overlaps=Contig1/1:1000;att=hand:fizzbin;overlaps=Contig1/5:200

That is, it is legal for the same feature filter ("overlaps")
to exist multiple times in the query.  If so there should
be a note pointing that out.


Are the following allowed?

1) an OR of the values for a region

   overlaps=Contig1/1:1000,Contig8/5:200

2) an OR of an att query

   att=hand:fizzbin,slark

3) and OR and an AND of the same attribute in an att filter

   att=hand:fizzbin,slark;att=hand:royal

This is the same as
   (hand contains "fizzbin" OR hand contains "slark") AND
   (hand contains "royal")

so would match "royal fizzbin" hands.

I think they are all legal.  I think I can improve
the wording a bit for clarification.


					Andrew
					dalke at dalkescientific.com