}
	alias event       = item event
	alias placeholder = item placeholder

	# TODO : Interactive operations.
	##
	# Navigation - Active item, day, track, time
	#
	# - Three axes: day, time, track
	#
	# - Day (numerically ordered 0, 1, ...):
	#   - f(irst), l(ast),
	#   - p(rev(ious)), n(ext)
	#
	# - Time (numerically ordered ascending from midnight):
	#   - t(op), b(ottom),
	#   - u(p)/f(orw(ard)), d(own)/back(ward)
	#
	# - Track (lexicographically ordered by name):
	#   - l(eft)m(ost), r(ight)m(ost)
	#   - l(eft), r(ight)
	##
	# Selection
	# - SetMark, FromMark, Include, Exclude
	# - Copy, Cut, Paste
	# = Selection limits: Single day, track ?
	# Enter/Close
	##

namespace eval ::cm {
    namespace export schedule
    namespace ensemble create
}
namespace eval ::cm::schedule {
    namespace export \
	active-or-select just-select validate \
	add remove rename select select-clear selected focus show listing test-known \
	test-select track-add track-remove track-rename test-track-known \
	test-track-select item-add-event item-add-placeholder test-item-day-known
    #item-remove item-rename
    namespace ensemble create

    namespace import ::cmdr::color
    namespace import ::cmdr::ask

    set pschedule [pschedule active_get]

    if {$pschedule eq {}} {
	puts \n[color note {No active schedule, operation ignored.}]
	return
    }

    set name [pschedule piece $pschedule dname]

    puts -nonewline "\nDeactivating schedule \"[color name $name]\" ... "
    flush stdout

    db do transaction {
	pschedule active_set {}
	pschedule validate

    set pschedule [pschedule active_get]

    if {$pschedule eq {}} {
	puts \n[color note {No active schedule}]
	return
    }

    set name [pschedule piece $pschedule dname]

    puts "\nActive schedule is \"[color name $name]\""
    return
}

proc ::cm::schedule::select {config} {
    debug.cm/schedule {}

	    # Extension: Mark the active track, and day.
	}
    }] show
    return
}

proc ::cm::schedule::focus {config} {
    debug.cm/schedule {}
    pschedule setup
    db show-location

    set pschedule [pschedule active_get]

    if {$pschedule eq {}} {
	puts \n[color note {No active schedule}]
	return
    }

    set name  [pschedule piece $pschedule dname]
    set focus [pschedule focus $pschedule]
    dict with focus {} ;# => xactive{item,day,track,time},xaitem{day,track,start,len}

    if {$xactivetrack ne {}} { set xactivetrack [track-piece $xactivetrack dname] }
    if {$xaitemtrack  ne {}} { set xaitemtrack  [track-piece $xaitemtrack  dname] }

    puts "\nFocus"
    [table/d t {
	$t add Schedule  $name
	if {$xactiveitem eq {}} {
	    # No item. Use saved historical data
	    $t add Day       $xactiveday
	    $t add Track     $xactivetrack
	    $t add Time      $xactivetime
	} else {
	    # Use item information, and show delta to historical
	    if {$xactiveday == $xaitemday} {
		$t add Day   "I $xaitemday"
	    } else {
		$t add Day   "I $xaitemday (-- $xactiveday)"
	    }
	    if {$xactivetrack eq $xaitemtrack} {
		$t add Track "I $xaitemtrack"
	    } else {
		$t add Track "I $xaitemtrack (-- $xactivetrack)"
	    }
	    $t add Time  "I $xaitemstart $xaitemlen (-- $xactivetime)" ;# -- TODO: format start, activetime
	}
    }] show
    return
}

# # ## ### ##### ######## ############# ######################

proc ::cm::schedule::TrackList {pschedule} {
    debug.cm/schedule {}
    set tracks {}

    set trackstats [pschedule track-name-counts $pschedule]
    # (name -> icount, sorted by name)

    # try to insert, report failure as user error
    puts -nonewline "Schedule \"[color name $pslabel]\": Creating track \"[color name $name]\" ... "
    flush stdout

    try {
	db do transaction {
	    set track [pschedule track-new $pschedule $name]

	    # New track is automatically active.
	    puts -nonewline "Activating ... "
	    flush stdout
	    pschedule track-active-set $pschedule $track

	    pschedule validate
	}
    } on error {e o} {
	# TODO: trap only proper insert error, if possible.
	util user-error $e SCHEDULE-TRACK CREATE
	return
    }

    puts "* Day:    $day"
    puts "* Start:  [pschedule-day 2external $start]"
    puts "* Length: $length"
    puts "* Note:   $note"

    try {
	db do transaction {
	    set item [pschedule item-new-event $pschedule $track $day $start $length $desc $note]

	    # New item is automatically active.
	    puts -nonewline "Activating ... "
	    flush stdout
	    pschedule item-active-set $pschedule $item

	    pschedule validate
	}
    } on error {e o} {
	# TODO: trap only proper insert error, if possible.
	util user-error $e SCHEDULE-ITEM CREATE
	return
    }

    puts "* Day:         $day"
    puts "* Start:       [pschedule-day 2external $start]"
    puts "* Length:      $length"
    puts "* Description: $description"

    try {
	db do transaction {
	    set item [pschedule item-new-placeholder $pschedule $track $day $start $length $label]

	    # New item is automatically active.
	    puts -nonewline "Activating ... "
	    flush stdout
	    pschedule item-active-set $pschedule $item

	    pschedule validate
	}
    } on error {e o} {
	# TODO: trap only proper insert error, if possible.
	util user-error $e SCHEDULE-ITEM CREATE
	return
    }