Table cdbtoplevel TopLevel_Command
	cdb
		subcmd	enum(Cdb/_SubCommand, "cdb subcommand")
		...	obj
	cdb-wr
		subcmd	enum(Cdbwr/_SubCommand, "cdb-wr subcommand")
		...	obj

Table cdb Cdb_SubCommand
	open
		path	string
		=>	iddata(&cdbtcl_databases)
	lookup
		db	iddata(&cdbtcl_databases)
		key	obj
		=>	obj
	lookup-hb
		db	iddata(&cdbtcl_databases)
		key	hb
		=>	hb
	close
		db	iddata(&cdbtcl_databases)

Table cdbwr Cdbwr_SubCommand
	create-empty
		pathb	string
		# files:
		#	<pathb>.main
		#	<pathb>.cdb
		#	<pathb>.log
		#	<pathb>.tmp (might be new .main or new .cdb)
		# invariants:
		#	.main is a cdb native text file
		#	  and always exists
		#	if .tmp exists it is irrelevant
		#	if .cdb exists it is a cdb database
		#	  containing exactly the same as .main
		#	if .log exists, it is a cdb native
		#	  text file _without the trailing newline_;
		#	  its contents override values from .main or .cdb
	open
		pathb	string
		on_info	obj
		=>	iddata(&cdbtcl_rwdatabases)
		# on_info <event> <xinfo>...:
		# on_info open-clean <statistics-info-string>
		# on_info open-dirty <statistics-info-string>
		# on_info compact-start <statistics-info-string>
		# on_info compact-end <statistics-info-string>
		# on_info close <statistics-info-string>
	lookup
		db	iddata(&cdbtcl_rwdatabases)
		key	obj
		=>	obj
	lookup-hb
		db	iddata(&cdbtcl_rwdatabases)
		key	hb
		=>	hb
	update
		db	iddata(&cdbtcl_rwdatabases)
		key	obj
		value	obj
	update-hb
		db	iddata(&cdbtcl_rwdatabases)
		key	hb
		value	hb
	update-quick
		db	iddata(&cdbtcl_rwdatabases)
		key	obj
		value	obj
	update-quick-hb
		db	iddata(&cdbtcl_rwdatabases)
		key	hb
		value	hb
	close
		db	iddata(&cdbtcl_rwdatabases)
	close-quick
		db	iddata(&cdbtcl_rwdatabases)