subgraph "logical_grouping" {
	style = rounded;
	bgcolor = gray95;
	color = gray;
	
	subgraph cluster_meta {
		label = <<b>meta</b>>;
		dbversion;
	}

	subgraph cluster_content {
		label = <<b>content</b>>;
		content;
	}

	subgraph cluster_directory {
		label = <<b>directories</b>>;
		directory;
		directory_entry_dir;
		directory_entry_file;
		directory_entry_rev;
		directory_list_dir;
		directory_list_file;
		directory_list_rev;

		{rank=same;
			directory_list_dir
			directory_list_file
			directory_list_rev}
		{rank=same;
			directory_entry_dir
			directory_entry_file
			directory_entry_rev}
	}

	subgraph cluster_revision {
		label = <<b>revisions</b>>;
		revision;
		revision_history;
		person;
	}

	subgraph cluster_release {
		label = <<b>releases</b>>;
		release;
	}

	subgraph cluster_occurrences {
		label = <<b>occurrences</b>>;
		occurrence;
		occurrence_history;
	}

	subgraph cluster_origins {
		label = <<b>origins</b>>;
		origin;
		fetch_history;
	}

	subgraph cluster_projects {
		label = <<b>projects</b>>;
		project;
		project_history;
	}

	subgraph cluster_organization {
		label = <<b>organizations</b>>;
		organization;
		list_history;
	}

	{
		edge [style = dashed];

		# "rtcolN" identifies the N-th row in a table, as a source
		# "ltcolN" identifies the N-th row in a table, as a destination
		"directory_entry_dir":rtcol2 -> "directory":ltcol1;
		"directory_entry_file":rtcol2 -> "content":ltcol2;
		"directory_entry_rev":rtcol2 -> "revision":ltcol1;
		"directory_list_dir":rtcol2 -> "directory_entry_dir":ltcol1;
		"directory_list_file":rtcol2 -> "directory_entry_file":ltcol1;
		"directory_list_rev":rtcol2 -> "directory_entry_rev":ltcol1;
		"release":rtcol2 -> "revision":ltcol1;
		"revision":rtcol7 -> "directory":ltcol1;
		"revision_history":rtcol2 -> "revision":ltcol1;
	}

}