diff --git a/gencat/pdf.c b/gencat/pdf.c
index 5e5cc0d..5949189 100644
--- a/gencat/pdf.c
+++ b/gencat/pdf.c
@@ -71,6 +71,9 @@ static struct format {
 static int total, done = 0;
 
 
+/* ----- Utility functions ------------------------------------------------- */
+
+
 static char *sanitize_name(const char *s)
 {
 	char *t, *tmp;
@@ -102,6 +105,9 @@ static void ps_string(FILE *file, const char *s)
 }
 
 
+/* ----- Alphabetic index -------------------------------------------------- */
+
+
 static void collect_names(const struct node *node, const char ***idx, int *n)
 {
 	const struct name *name;
@@ -181,6 +187,9 @@ static void make_index(FILE *file, const struct node *node)
 }
 
 
+/* ----- Overlay and table of contents ------------------------------------- */
+
+
 static int children(const struct node *node)
 {
 	int n = 0;
@@ -266,6 +275,9 @@ static void print_comment(FILE *file, const struct line *comment)
 }
 
 
+/* ----- Component conversion ---------------------------------------------- */
+
+
 static void cat(FILE *out, const char *name)
 {
 	FILE *in;
@@ -343,6 +355,9 @@ static void convert_tree(const struct node *node, FILE *out)
 }
 
 
+/* ----- Setup and PDF generation ------------------------------------------ */
+
+
 static int count_tree(const struct node *node)
 {
 	int sum = 0;