This track depicts gaps in the assembly. These gaps - with the exception of intractable heterochromatic gaps - will be closed during the finishing process.
Gaps are represented as black boxes in this track. If the relative order and orientation of the contigs on either side of the gap is known, it is a bridged gap and a white line is drawn through the black box representing the gap.
This assembly contains the following principal types of gaps:
NCBI discussion of genome assembly procedures.
The Feb. 2009 human reference sequence (GRCh37) was produced by the Genome Reference Consortium.