 @_cellnames_from_quadkeys = ( me, quadkeys ) ->
   R = new Set()
   for quadkey in quadkeys
-    R.add cellname for cellname in me.quadcells
+    continue unless ( quadcells = me.quadcells[ quadkey ] )?
+    R.add cellname for cellname in quadcells
   return ( cellname for cellname from R )
 
 

      col_letter  = ( EXCJSCC.n2l col_nr ).toLowerCase()
      designation = "#{col_letter}#{row_nr}"
      yield { col_nr, row_nr, col_letter, designation, }
  yield return



    throw new Error "(MKTS/TABLE 6043) expected a text for cellborder, got a #{rpr type}"
  unless ( groups = cellborder.match /^(.+):(.+):(.*)$/ )?
    throw new Error "(MKTS/TABLE 5822) expected a cellborder like 'a1:left:sDashed,sThick', got #{rpr cellborder}"
  [ _, cellhints, sides, style, ] = groups
  #.........................................................................................................
  sides = ( _.trim() for _ in sides.split ',' )
  sides = [ 'top', 'left', 'bottom', 'right', ] if '*' in sides
  #.........................................................................................................
  ### TAINT this will have to be changed to allow for named cells ###
  cellhints = new Set ( _.trim() for _ in cellhints.split ',' )
  if cellhints.has '*'
    cells = Object.keys me.cellquads
  else
    ### TAINT as it stands, `cellborder'table:bottom,right:red'` will style all bottom and right borders
    of all cells that have real estate along the bottom and right borders of the table. An improved version
    should probably only affect the bottom borders of table-bottom cells and the right borders of
    table-right cells. Use two statements `cellborder'table:bottom:red'`, `cellborder'table:right:red'` to
    express that meaning FTTB. ###
    if cellhints.has 'table'
      cellhints.delete 'table'
      for side in sides
        cellhints.add d.quadkey for d from @_walk_table_edge_quads me, side
    quadkeys  = ( cellhint for cellhint from cellhints )
    cells     = @_cellnames_from_quadkeys me, quadkeys
  #.........................................................................................................
  style = style.trim()
  style = null if style in [ 'none', '', ]
