From Array Suite Wiki
The Genome Coverage Format (GCF) is a custom data format, designed by OmicSoft, that enables compact, streaming NGS coverage data for display in Genome Browsers. It is much more compact than coverage formats like Wiggle (.wig) or BedGraph (.bedgraph), but maintains base-pair resolution.
Create a GCF File
From BAM files
From BAS files
.bas files can be converted to .gcf files by running a BasTools omicscript.
Genome Browser Track
.gcf files can be added to a compatible Genome Browser instance by selecting Add Track | Add Track from (Local/Server) File,
then selecting Numeric Track | GCF File or Multiple GCF files - group.