4 files changed, 49 insertions, 8 deletions

diff --git a/eqn.7 b/eqn.7
index 9e558d6d..083f2b64 100644
--- a/eqn.7
+++ b/eqn.7
@@ -67,9 +67,15 @@ box     : text
         | DEFINE text text
         | SET text text
         | UNDEF text
+        | box pos box
         | box mark
         | font box
 text    : TEXT
+pos     : OVER
+        | SUP
+        | SUB
+        | TO
+        | FROM
 mark	: DOT
         | DOTDOT
         | HAT
diff --git a/eqn.c b/eqn.c
index 37488919..b4087f26 100644
--- a/eqn.c
+++ b/eqn.c
@@ -80,11 +80,22 @@ static	const struct eqnstr eqnmarks[EQNMARK__MAX] = {
 };
 
 static	const struct eqnstr eqnfonts[EQNFONT__MAX] = {
+	{ "", 0 },
 	{ "roman", 5 },
 	{ "bold", 4 },
 	{ "italic", 6 },
 };
 
+static	const struct eqnstr eqnposs[EQNPOS__MAX] = {
+	{ "", 0 },
+	{ "over", 4 },
+	{ "sup", 3 },
+	{ "sub", 3 },
+	{ "to", 2 },
+	{ "from", 4 },
+	{ "above", 5 },
+};
+
 /* ARGSUSED */
 enum rofferr
 eqn_read(struct eqn_node **epp, int ln, 
@@ -189,8 +200,7 @@ eqn_box(struct eqn_node *ep, struct eqn_box *last, struct eqn_box **sv)
 
 	*sv = last;
 	nextc = 1;
-	font = EQNFONT_NONE;
-
+	font = EQNFONT_NONE;  
 again:
 	if (NULL == (start = eqn_nexttok(ep, &sz)))
 		return(0);
@@ -204,6 +214,15 @@ again:
 		goto again;
 	}
 
+	for (i = 0; i < (int)EQNFONT__MAX; i++) {
+		if (eqnposs[i].sz != sz)
+			continue;
+		if (strncmp(eqnposs[i].name, start, sz))
+			continue;
+		last->pos = (enum eqn_post)i;
+		goto again;
+	}
+
 	for (i = 0; i < (int)EQN__MAX; i++) {
 		if (eqnparts[i].str.sz != sz)
 			continue;
diff --git a/mandoc.h b/mandoc.h
index 231497e9..68ae3b02 100644
--- a/mandoc.h
+++ b/mandoc.h
@@ -306,6 +306,17 @@ enum	eqn_fontt {
 	EQNFONT__MAX
 };
 
+enum	eqn_post {
+	EQNPOS_NONE = 0,
+	EQNPOS_OVER,
+	EQNPOS_SUP,
+	EQNPOS_SUB,
+	EQNPOS_TO,
+	EQNPOS_FROM,
+	EQNPOS_ABOVE,
+	EQNPOS__MAX
+};
+
  /*
  * A "box" is a parsed mathematical expression as defined by the eqn.7
  * grammar.
@@ -314,11 +325,16 @@ struct	eqn_box {
 	enum eqn_boxt	  type; /* type of node */
 	struct eqn_box	 *child; /* child node */
 	struct eqn_box	 *next; /* next in tree */
+	enum eqn_post	  pos; /* position of next box */
 	char		 *text; /* text (or NULL) */
 	enum eqn_markt	  mark; /* a mark about the box */
 	enum eqn_fontt	  font; /* font of box */
 };
 
+/*
+ * An equation consists of a tree of expressions starting at a given
+ * line and position. 
+ */
 struct	eqn {
 	struct eqn_box	 *root; /* root mathematical expression */
 	int		  ln; /* invocation line */
diff --git a/tree.c b/tree.c
index 722e396c..22f91a10 100644
--- a/tree.c
+++ b/tree.c
@@ -270,18 +270,18 @@ print_box(const struct eqn_box *ep, int indent)
 
 	switch (ep->type) {
 	case (EQN_ROOT):
-		printf("eqn-root(%d, %d)\n", 
-				ep->font, ep->mark);
+		printf("eqn-root(%d, %d, %d)\n", 
+			ep->pos, ep->font, ep->mark);
 		print_box(ep->child, indent + 1);
 		break;
 	case (EQN_SUBEXPR):
-		printf("eqn-subxpr(%d, %d)\n", 
-				ep->font, ep->mark);
+		printf("eqn-subxpr(%d, %d, %d)\n", 
+			ep->pos, ep->font, ep->mark);
 		print_box(ep->child, indent + 1);
 		break;
 	case (EQN_TEXT):
-		printf("eqn-text(%d, %d): [%s]\n", 
-				ep->font, ep->mark, ep->text);
+		printf("eqn-text(%d, %d, %d): [%s]\n", 
+			ep->pos, ep->font, ep->mark, ep->text);
 		break;
 	default:
 		break;