(defun c:acelayer ( / flag ed x rec laynam layer_mapping layer_restore)
  ; PURPOSE: adjust default layer color assignments for switch to light background.
  ;    For example, change yellow-color layers to a color that displays better on a
  ;    white or light background. Also restore WIRENO and WIREFIXED layers and color
  ;    assignments if these two layers appear to have been purged from the drawing.
  ;
  (setq layer_mapping 
    (list  ; format is (list layernam newcolor)
      (list "WIRENO" 72) ; light green (70) --> shade darker
      (list "WIREFIXED" 7) ; light blue (130) --> black/white 
      (list "WIREREF" 52) ; light green (61) --> darker olive green
      (list "WIREREF_DEST" 52) ; light green (61) --> darker olive green
      (list "MISC" 7) ; yellow --> black/white
      (list "PMISC" 7) ; yellow --> black/white
      (list "PTAG" 150) ; light yellow (51) --> medium blue
      (list "TAGS" 150) ; light yellow (51) --> medium blue
      (list "TERMS" 123) ; cyan --> gray/blue
  ) )
  
  (setq layer_restore
    (list  ; format is (list layername color linetype)
      (list "WIRENO" 72 "Continuous")
      (list "WIREFIXED" 7 "Continuous")
    )
  )
  (setvar "CMDECHO" 0)
  (setq flag T) ; flag to rewind to beginning of LAYER table
  (while (/= (setq ed (tblnext "LAYER" flag)) nil)
    (setq flag nil) ; clear the rewind flag
    (setq laynam (strcase (cdr (assoc 2 ed)))) ; forced to upper case 
    ; Look for layer name match in "layer_mapping"
    (foreach rec layer_mapping
      (if (AND (= (car rec) laynam) ; found match on name
               (/= (cadr rec) (cdr (assoc 62 ed)))) ; mismatch on color assignment
        (progn ; flip color assignment for this layer
          (command "_.LAYER" "_C")
          (command (itoa (cadr rec)))
          (command (car rec))
          (command "")
          (princ "\nLayer ")
          (princ (car rec))
          (princ " ")
          (princ (cdr (assoc 62 ed)))
          (princ " --> ")
          (princ (cadr rec))       
    ) ) )
  )  
  ; restore any missing layers               
  (foreach rec layer_restore
    (setq laynam (car rec))
    (if (not (tblsearch "LAYER" laynam))
      (progn ; layer not found, create it now
        (command "_.LAYER" "_N" laynam "_C" (itoa (cadr rec)) laynam "_Ltype" (caddr rec) laynam "")
        (princ "\nRestored layer ")
        (princ laynam)
        (princ " color=")
        (princ (cadr rec))
        (princ " ltype=")
        (princ (caddr rec))
  ) ) )      
  (princ)
)