diff --git a/sch2fig/cairo.c b/sch2fig/cairo.c
index aeb080d..42384ce 100644
--- a/sch2fig/cairo.c
+++ b/sch2fig/cairo.c
@@ -116,7 +116,8 @@ static void paint(cairo_t *cr, int color, int fill_color)
 /* ----- General items ----------------------------------------------------- */
 
 
-static void cr_poly(void *ctx, int points, int x[points], int y[points],
+static void cr_poly(void *ctx,
+    int points, const int x[points], const int y[points],
     int color, int fill_color, unsigned layer)
 {
 	struct cairo_ctx *cc = ctx;
diff --git a/sch2fig/fig.c b/sch2fig/fig.c
index ef1e90c..59b5c31 100644
--- a/sch2fig/fig.c
+++ b/sch2fig/fig.c
@@ -84,7 +84,8 @@ static void fig_rect(void *ctx, int sx, int sy, int ex, int ey,
 }
 
 
-static void fig_poly(void *ctx, int points, int x[points], int y[points],
+static void fig_poly(void *ctx,
+    int points, const int x[points], const int y[points],
     int color, int fill_color, unsigned layer)
 {
 	int i;
@@ -152,6 +153,14 @@ static void fig_arc(void *ctx, int x, int y, int r, int sa, int ea,
 }
 
 
+static void fig_tag(void *ctx, const char *s,
+    int points, const int x[points], const int y[points])
+{
+	printf("# href=\"%s\" alt=\"\"\n", s);
+	fig_poly(ctx, points, x, y, COLOR_NONE, COLOR_NONE, 999);
+}
+
+
 static void fig_text(void *ctx, int x, int y, const char *s, unsigned size,
     enum text_align align, int rot, unsigned color, unsigned layer)
 {
@@ -275,6 +284,7 @@ const struct gfx_ops fig_ops = {
 	.circ		= fig_circ,
 	.arc		= fig_arc,
 	.text		= fig_text,
+	.tag		= fig_tag,
 	.text_width	= fig_text_width,
 	.init		= fig_init,
 };
diff --git a/sch2fig/gfx.c b/sch2fig/gfx.c
index 6dc90e8..7234fe2 100644
--- a/sch2fig/gfx.c
+++ b/sch2fig/gfx.c
@@ -52,7 +52,7 @@ void gfx_rect(int sx, int sy, int ex, int ey,
 }
 
 
-void gfx_poly(int points, int x[points], int y[points],
+void gfx_poly(int points, const int x[points], const int y[points],
     int color, int fill_color, unsigned layer)
 {
 	gfx_ops->poly(gfx_ctx, points, x, y, color, fill_color, layer);
@@ -79,6 +79,14 @@ void gfx_text(int x, int y, const char *s, unsigned size,
 }
 
 
+void gfx_tag(const char *s,
+    unsigned points, const int x[points], int const y[points])
+{
+	if (gfx_ops->tag)
+		gfx_ops->tag(gfx_ctx, s, points, x, y);
+}
+
+
 unsigned gfx_text_width(const char *s, unsigned size)
 {
 	return gfx_ops->text_width(gfx_ctx, s, size);
diff --git a/sch2fig/gfx.h b/sch2fig/gfx.h
index bdbb124..4500c9e 100644
--- a/sch2fig/gfx.h
+++ b/sch2fig/gfx.h
@@ -25,7 +25,8 @@ struct gfx_ops {
 	    int color, unsigned layer);
 	void (*rect)(void *ctx, int sx, int sy, int ex, int ey,
 	    int color, int fill_color, unsigned layer);
-	void (*poly)(void *ctx, int points, int x[points], int y[points],
+	void (*poly)(void *ctx,
+	    int points, const int x[points], const int y[points],
 	    int color, int fill_color, unsigned layer);
 	void (*circ)(void *ctx, int x, int y, int r,
 	    int color, int fill_color, unsigned layer);
@@ -33,6 +34,8 @@ struct gfx_ops {
 	    int color, int fill_color, unsigned layer);
 	void (*text)(void *ctx, int x, int y, const char *s, unsigned size,
 	    enum text_align align, int rot, unsigned color, unsigned layer);
+	void (*tag)(void *ctx,  const char *s,
+	    int points, const int x[points], const int y[points]);
 	unsigned (*text_width)(void *ctx, const char *s, unsigned size);
 	void *(*init)(int argc, char *const *argv);
 	void (*new_sheet)(void *ctx);
@@ -45,13 +48,15 @@ struct gfx_ops {
 void gfx_line(int sx, int sy, int ex, int ey, int color, unsigned layer);
 void gfx_rect(int sx, int sy, int ex, int ey,
     int color, int fill_color, unsigned layer);
-void gfx_poly(int points, int x[points], int y[points],
+void gfx_poly(int points, const int x[points], const int y[points],
     int color, int fill_color, unsigned layer);
 void gfx_circ(int x, int y, int r, int color, int fill_color, unsigned layer);
 void gfx_arc(int x, int y, int r, int sa, int ea,
     int color, int fill_color, unsigned layer);
 void gfx_text(int x, int y, const char *s, unsigned size,
     enum text_align align, int rot, unsigned color, unsigned layer);
+void gfx_tag(const char *s, 
+    unsigned points, const int x[points], int const y[points]);
 unsigned gfx_text_width(const char *s, unsigned size);
 
 /* inititalization and termination */
diff --git a/sch2fig/layer.c b/sch2fig/layer.c
index 7b3eb6c..598dbbb 100644
--- a/sch2fig/layer.c
+++ b/sch2fig/layer.c
@@ -153,7 +153,8 @@ void layer_rect(void *ctx, int sx, int sy, int ex, int ey,
 }
 
 
-void layer_poly(void *ctx, int points, int x[points], int y[points],
+void layer_poly(void *ctx,
+    int points, const int x[points], const int y[points],
     int color, int fill_color, unsigned layer)
 {
 	struct layer *lc = ctx;
diff --git a/sch2fig/layer.h b/sch2fig/layer.h
index e7caae4..d265111 100644
--- a/sch2fig/layer.h
+++ b/sch2fig/layer.h
@@ -39,7 +39,7 @@ void layer_line(void *ctx, int sx, int sy, int ex, int ey,
     int color, unsigned layer);
 void layer_rect(void *ctx, int sx, int sy, int ex, int ey,
     int color, int fill_color, unsigned layer);
-void layer_poly(void *ctx, int points, int x[points], int y[points],
+void layer_poly(void *ctx, int points, const int x[points], const int y[points],
     int color, int fill_color, unsigned layer);
 void layer_circ(void *ctx, int x, int y, int r,
     int color, int fill_color, unsigned layer);