diff --git a/b2/Makefile b/b2/Makefile
new file mode 100644
index 0000000..781f643
--- /dev/null
+++ b/b2/Makefile
@@ -0,0 +1,66 @@
+#
+# Makefile - BOOM's Makefile
+#
+# Copyright 2012 by Werner Almesberger
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+
+CFLAGS = -Wall $(shell pkg-config --cflags glib-2.0)
+SLOPPY = -Wno-unused -Wno-implicit-function-declaration
+OBJS = boom.o chr.o comp.o db.o eval.o param.o util.o lex.yy.o y.tab.o
+LDLIBS = -lfl $(shell pkg-config --libs glib-2.0)
+
+YACC = bison -y
+YYFLAGS = -v
+
+CC_normal	:= $(CC)
+YACC_normal	:= $(YACC)
+LEX_normal	:= $(LEX)
+DEPEND_normal	:= $(CPP) $(CFLAGS) -MM -MG
+
+CC_quiet	= @echo "  CC       " $@ && $(CC_normal)
+YACC_quiet	= @echo "  YACC     " $@ && $(YACC_normal)
+LEX_quiet	= @echo "  LEX      " $@ && $(LEX_normal)
+GEN_quiet	= @echo "  GENERATE " $@ &&
+DEPEND_quiet	= @$(DEPEND_normal)
+
+ifeq ($(V),1)
+	CC	= $(CC_normal)
+	LEX	= $(LEX_normal)
+	YACC	= $(YACC_normal)
+	GEN	=
+	DEPEND	= $(DEPEND_normal)
+else
+	CC	= $(CC_quiet)
+	LEX	= $(LEX_quiet)
+	YACC	= $(YACC_quiet)
+	GEN	= $(GEN_quiet)
+	DEPEND	= $(DEPEND_quiet)
+endif
+
+.PHONY:	all clean
+
+all:		boom
+
+boom:		$(OBJS)
+		$(CC) $(CFLAGS) -o $@ $(OBJS) $(LDLIBS)
+
+lex.yy.c:	lang.l y.tab.h
+		$(LEX) lang.l
+
+lex.yy.o:	lex.yy.c y.tab.h
+		$(CC) -c $(CFLAGS) $(SLOPPY) lex.yy.c
+
+y.tab.c y.tab.h: lang.y
+		$(YACC) $(YYFLAGS) -d lang.y
+
+y.tab.o:	y.tab.c
+		$(CC) -c $(CFLAGS) $(SLOPPY) y.tab.c
+
+clean:
+		rm -f $(OBJS)
+		rm -f lex.yy.c y.tab.c y.tab.h
diff --git a/b2/bitset.h b/b2/bitset.h
new file mode 100644
index 0000000..6b7f611
--- /dev/null
+++ b/b2/bitset.h
@@ -0,0 +1,82 @@
+/*
+ * bitset.h - Bit sets
+ *
+ * Copyright 2012 by Werner Almesberger
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#ifndef BITSET_H
+#define	BITSET_H
+
+#include <stdint.h>
+
+#include "bitset.h"
+
+
+struct bitset {
+	uint64_t v;
+};
+
+
+static inline void bitset_zero(struct bitset *b)
+{
+	b->v = 0;
+}
+
+
+static inline void bitset_set(struct bitset *b, int n)
+{
+	b->v |= (uint64_t) 1 << n;
+}
+
+
+static inline void bitset_clear(struct bitset *b, int n)
+{
+	b->v &= ~((uint64_t) 1 << n);
+}
+
+
+static inline int bitset_get(const struct bitset *b, int n)
+{
+	return !!(b->v & ((uint64_t) 1 << n));
+}
+
+
+static inline int bitset_empty(const struct bitset *b)
+{
+	return !!b->v;
+}
+
+
+static inline int bitset_first(const struct bitset *b)
+{
+	int i;
+
+	for (i = 0; i != sizeof(b->v)*8; i++)
+		if (b->v & ((uint64_t) 1 << i))
+			return i;
+	return -1;
+}
+
+
+static inline int bitset_last(const struct bitset *b)
+{
+	int i = sizeof(b->v)*8;
+
+	while (--i)
+		if (b->v & ((uint64_t) 1 << i))
+			break;
+	return i;
+}
+
+
+static inline int bitset_common(const struct bitset *a, const struct bitset *b)
+{
+	return (a->v & b->v) != 0;
+}
+
+#endif /* !BITSET_H */
diff --git a/b2/boom.c b/b2/boom.c
new file mode 100644
index 0000000..31dbf45
--- /dev/null
+++ b/b2/boom.c
@@ -0,0 +1,4 @@
+int main(void)
+{
+	return 0;
+}
diff --git a/b2/chr.c b/b2/chr.c
new file mode 100644
index 0000000..d813725
--- /dev/null
+++ b/b2/chr.c
@@ -0,0 +1,102 @@
+/*
+ * chr.h - Part characteristics
+ *
+ * Copyright 2012 by Werner Almesberger
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+
+#include "util.h"
+#include "param.h"
+#include "chr.h"
+
+
+struct condition {
+	struct value value;
+	enum relop relop;
+	struct condition *next;
+};
+
+struct selector {
+	struct condition *cond;
+	struct selector *next;
+};
+
+struct field {
+	const char *name;
+	const struct format *fmt;
+	struct field *mark;
+	struct selector *sel;
+	struct field *next;
+};
+
+static struct field *fields = NULL, *curr_field = NULL, *mark = NULL;
+
+
+const struct format *field_find(const char *name)
+{
+	const struct field *f;
+
+	for (f = fields; f; f = f->next)
+		if (f->name == name)
+			return f->fmt;
+	return NULL;
+}
+
+
+void field_add(const char *name, const struct format *fmt)
+{
+	struct field *field;
+
+	if (field_find(name))
+		yyerrorf("duplicate field \"%s\"", name);
+	field = alloc_type(struct field);
+	field->name = name;
+	field->fmt = fmt;
+	field->mark = (void *) 1; /* poison */
+	field->sel = NULL;
+	if (curr_field)
+		curr_field->next = field;
+	else
+		fields = field;
+	curr_field = field;
+}
+
+
+void field_mark(void)
+{
+	if (mark)
+		mark->mark = curr_field;
+	mark = curr_field;
+}
+
+
+void field_release(void)
+{
+	curr_field = mark;
+	if (curr_field)
+		mark = curr_field->mark;
+}
+
+
+void field_add_selector(enum relop relop, const char *word)
+{
+	
+}
+
+
+void field_more_selectors(void)
+{
+	if (curr_field->fmt->ops != &param_ops_set)
+		;//yyerrorf("
+}
+
+
+void field_add_wildcard(void)
+{
+}
+
diff --git a/b2/chr.h b/b2/chr.h
new file mode 100644
index 0000000..73168df
--- /dev/null
+++ b/b2/chr.h
@@ -0,0 +1,27 @@
+/*
+ * chr.h - Part characteristics
+ *
+ * Copyright 2012 by Werner Almesberger
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+
+#ifndef CHR_H
+#define	CHR_H
+
+#include "param.h"
+
+
+void field_add(const char *name, const struct format *fmt);
+const struct format *field_find(const char *name);
+void field_mark(void);
+void field_release(void);
+void field_add_selector(enum relop relop, const char *word);
+void field_more_selectors(void);
+void field_add_wildcard(void);
+
+#endif /* !CHR_H */
diff --git a/b2/comp.c b/b2/comp.c
new file mode 100644
index 0000000..2d2abeb
--- /dev/null
+++ b/b2/comp.c
@@ -0,0 +1,110 @@
+/*
+ * comp.c - Parameter comparison
+ *
+ * Copyright 2012 by Werner Almesberger
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+
+#include "bitset.h"
+#include "param.h"
+
+
+#define	EQUAL(relop)	((relop) & (rel_le | rel_eq | rel_ge))
+#define	LESS(relop)	((relop) & (rel_lt | rel_le))
+#define	GREATER(relop)	((relop) & (rel_ge | rel_gt))
+
+
+static int do_comp_name(const char *a, enum relop relop, const char *b)
+{
+	int cmp;
+
+	if (EQUAL(relop))
+		return a == b;
+	cmp = strcmp(a, b);
+	assert(cmp);
+	if (cmp < 0)
+		return LESS(relop);
+	else
+		return GREATER(relop);
+}
+
+
+int comp_name(const struct value *a, enum relop relop, const struct value *b)
+{
+	return do_comp_name(a->u.name, relop, b->u.name);
+}
+
+
+static int do_comp_set(const struct bitset *a, enum relop relop,
+    const struct bitset *b)
+{
+	assert(!bitset_empty(a));
+	assert(!bitset_empty(b));
+	if (EQUAL(relop) && bitset_common(a, b))
+		return 1;
+	if (LESS(relop) && bitset_first(a) < bitset_last(b))
+		return 1;
+	if (GREATER(relop) && bitset_last(a) > bitset_first(b))
+		return 1;
+	return 0;
+}
+
+
+int comp_set(const struct value *a, enum relop relop, const struct value *b)
+{
+	return do_comp_set(&a->u.set, relop, &b->u.set);
+}
+
+
+static int do_comp_abs(double a, enum relop relop, double b)
+{
+	if (a == b)
+		return EQUAL(relop);
+	if (a < b)
+		return LESS(relop);
+	else
+		return GREATER(relop);
+}
+
+
+int comp_abs(const struct value *a, enum relop relop, const struct value *b)
+{
+	return do_comp_abs(a->u.abs, relop, b->u.abs);
+}
+
+
+static int do_comp_rel(const struct rel_value *a, enum relop relop,
+    const struct rel_value *b)
+{
+	if (a->fract != b->fract)
+		return 0;
+	if (a->plus == b->plus && a->minus == b->minus)
+		return EQUAL(relop);
+	if (a->plus <= b->plus && a->minus <= b->minus)
+		return LESS(relop);
+	if (a->plus >= b->plus && a->minus >= b->minus)
+		return GREATER(relop);
+	return 0;
+}
+
+
+int comp_rel(const struct value *a, enum relop relop, const struct value *b)
+{
+	return do_comp_rel(&a->u.rel, relop, &b->u.rel);
+}
+
+
+int compare(const struct format *fmt,
+    const struct value *a, enum relop relop, const struct value *b)
+{
+	return fmt->ops->comp(a, relop, b);
+}
diff --git a/b2/db.c b/b2/db.c
new file mode 100644
index 0000000..1f45359
--- /dev/null
+++ b/b2/db.c
@@ -0,0 +1,82 @@
+/*
+ * db.c - Parts database
+ *
+ * Copyright 2012 by Werner Almesberger
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+
+#include <glib.h>
+
+#include "util.h"
+#include "db.h"
+
+
+static GTree *tree = NULL;
+
+
+static gint comp(gconstpointer a, gconstpointer b)
+{
+	const struct part *pa = a;
+	const struct part *pb = b;
+
+	/*
+	 * Just subtracting the pointers may produce values outside the
+	 * range of gint values.
+	 */
+	return pa->domain == pb->domain ?
+	    pa->name < pb->name ? -1 : pa->name > pb->name ? 1 : 0 :
+	    pa->domain < pb->domain ? -1 : 1;
+}
+
+
+struct part *part_lookup(const char *domain, const char *name)
+{
+	struct part part = {
+		.domain = domain,
+		.name = name,
+	};
+
+	if (!tree)
+		return NULL;
+	return g_tree_lookup(tree, &part);
+}
+
+
+struct part *part_add(const char *domain, const char *name)
+{
+	struct part part = {
+		.domain = domain,
+		.name = name,
+	};
+	struct part *p;
+
+	if (!tree)
+		tree = g_tree_new(comp);
+	p = g_tree_lookup(tree, &part);
+	if (!p) {
+		p = alloc_type(struct part);
+		p->stock = NULL;
+		p->next = p->prev = p;
+		g_tree_insert(tree, p, p);
+	}
+	return p;
+}
+
+
+void part_alias(struct part *a, struct part *b)
+{
+	struct part *tmp, *tmp2;
+
+	tmp = a->next;
+	a->next = b;
+	b->prev->next = tmp;
+
+	tmp2 = b->prev;
+	b->prev = a;
+	tmp->prev = tmp2;
+}
diff --git a/b2/db.h b/b2/db.h
new file mode 100644
index 0000000..db6ec41
--- /dev/null
+++ b/b2/db.h
@@ -0,0 +1,66 @@
+/*
+ * db.h - Parts database
+ *
+ * Copyright 2012 by Werner Almesberger
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+
+#ifndef DB_H
+#define	DB_H
+
+struct exchange {
+	const struct currency *dst;
+	double factor;
+	struct exchange *next;
+};
+
+struct currency {
+	const char *name;
+	struct exchange *exchange;
+	struct currency *next;
+};
+
+struct price {
+	int qty;	/* order quantity */
+	double value;	/* per quantity cost */
+	const struct currency *curr;
+	int fract;	/* 0 if > qty at same price; 1 if multiples of qty */
+	struct price *next; /* next lower qty */
+};
+
+struct provider {
+	const char *name;
+	double shipping; /* S&H cost */
+	double minimum;	/* minimum order */
+	const struct currency *curr;
+	struct provider *next;
+};
+
+struct stock {
+	int avail;	/* items in stock */
+	int package;	/* "natural" quantity (reel, tray, bag, etc.) */
+	struct price *manual; /* single parts, for manual assembly only */
+	double reeling;	/* cost of converting "manual" to "fab"; <0 if n/a */
+	struct price *fab; /* for automated assembly */
+} stock;
+
+struct part {
+	const char *domain;
+	const char *name;
+	struct param *param;	/* NULL if @@@ */
+	struct stock *stock;	/* NULL if vendor part */
+	struct part *next;	/* alias loop (cyclic) */
+	struct part *prev;
+};
+
+
+struct part *part_lookup(const char *domain, const char *name);
+struct part *part_add(const char *domain, const char *name);
+void part_alias(struct part *a, struct part *b);
+
+#endif /* !DB_H */
diff --git a/b2/eval.c b/b2/eval.c
new file mode 100644
index 0000000..dc3d804
--- /dev/null
+++ b/b2/eval.c
@@ -0,0 +1,216 @@
+/*
+ * eval.c - String to parameter
+ *
+ * Copyright 2012 by Werner Almesberger
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+
+#include "bitset.h"
+#include "param.h"
+
+
+int eval_name(const struct format *fmt, const char *s, struct value *res)
+{
+	res->u.name = s;
+	return 1;
+}
+
+
+static int lookup_name(const struct names *name, const char *s)
+{
+	const struct equiv *eq;
+	int n;
+
+	for (n = 0; name; n++)
+		for (eq = name->equiv; eq; eq = eq->next)
+			if (eq->name == s)
+				return n;
+	return -1;
+}
+
+
+int eval_set(const struct format *fmt, const char *s, struct value *res)
+{
+	int n;
+
+	bitset_zero(&res->u.set);
+	n = lookup_name(fmt->u.set, s);
+	if (n < 0)
+		return 0;
+	bitset_set(&res->u.set, n);
+	return 1;
+}
+
+
+static int decode_mult(char c, double *mult)
+{
+	switch (c) {
+	case 'f':
+		*mult = 1e-15;
+		return 1;
+	case 'p':
+		*mult = 1e-12;
+		return 1;
+	case 'n':
+		*mult = 1e-9;
+		return 1;
+	case 'u':
+		*mult = 1e-6;
+		return 1;
+	case 'm':
+		*mult = 1e-3;
+		return 1;
+	case 'k':
+		*mult = 1e3;
+		return 1;
+	case 'M':
+		*mult = 1e6;
+		return 1;
+	default:
+		return 0;
+	}
+}
+
+
+static int strip_unit(const char *s, const char **stop, const char *unit,
+    double *mult)
+{
+	int n;
+
+	n = strlen(unit);
+	if (*stop-n < s)
+		return 0;
+	if (!strcmp(*stop-n, unit))
+		*stop -= n;
+	if (*stop > s) {
+		if (decode_mult((*stop)[-1], mult))
+			(*stop)--;
+		else
+			*mult = 1;
+			
+	} else {
+		*mult = 1;
+	}
+	return 1;
+}
+
+
+int eval_abs(const struct format *fmt, const char *s,
+    struct value *res)
+{
+	const char *slash, *stop;
+	char *end;
+	double mult, a, b;
+
+	stop = strchr(s, 0);
+	if (!strip_unit(s, &stop, fmt->u.abs, &mult))
+		return 0;
+	slash = strchr(s, '/');
+	if (!slash) {
+		res->u.abs = strtod(s, &end)*mult;
+		return end == stop;
+	}
+	a = strtod(s, &end);
+	if (end != slash)
+		return 0;
+	b = strtod(slash+1, &end);
+	if (end != stop)
+		return 0;
+	res->u.abs = a/b*mult;
+	return 1;
+}
+
+
+static int plusminus(const char *s, const char *slash, const char *stop,
+    double *plus, double *minus)
+{
+	char *end;
+
+	if (s == slash || slash == stop)
+		return 0;
+
+	/* -M/+P */
+	if (*s == '-') {
+		if (slash[1] != '+')
+			return 0;
+		*minus = strtod(s+1, &end);
+		if (end != slash)
+			return 0;
+		*plus = strtod(slash+2, &end);
+		return end == stop;
+	}
+
+	/* +P/-M */
+	if (*s == '+') {
+		if (slash[1] != '-')
+			return 0;
+		*plus = strtod(s+1, &end);
+		if (end != slash)
+			return 0;
+		*minus = strtod(slash+2, &end);
+		return end == stop;
+	}
+
+	/* M/P */
+	*minus = strtod(s, &end);
+	if (end != slash)
+		return 0;
+	*plus = strtod(slash+1, &end);
+	return end == stop;
+}
+
+
+static int relative(const char *s, const char *stop, double *plus,
+    double *minus)
+{
+	const char *slash;
+	char *end;
+
+	slash = strchr(s, '/');
+	if (slash >= stop)
+		return 0;
+	if (slash)
+		return plusminus(s, slash, stop, plus, minus);
+	*plus = *minus = strtod(s, &end);
+	return *plus >= 0 && end == stop;
+}
+
+
+int eval_rel(const struct format *fmt, const char *s,
+    struct value *res)
+{
+	const char *perc, *stop;
+	double mult = 1;
+
+	perc = strchr(s, '%');
+	res->u.rel.fract = !!perc;
+	if (perc) {
+		if (perc[1])
+			return 0;
+		return relative(s, perc, &res->u.rel.plus, &res->u.rel.minus);
+	}
+	assert(fmt->u.rel->ops == &param_ops_abs);
+	stop = strchr(s, 0);
+	if (!strip_unit(s, &stop, fmt->u.rel->u.abs, &mult))
+		return 0;
+	if (!relative(s, perc, &res->u.rel.plus, &res->u.rel.minus))
+		return 0;
+	res->u.rel.plus *= mult;
+	res->u.rel.minus *= mult;
+	return 1;
+}
+
+
+int evaluate(const struct format *fmt, const char *s, struct value *res)
+{
+	return fmt->ops->eval(fmt, s, res);
+}
diff --git a/b2/lang.l b/b2/lang.l
new file mode 100644
index 0000000..766104d
--- /dev/null
+++ b/b2/lang.l
@@ -0,0 +1,59 @@
+%{
+/*
+ * lang.l - BOOM syntax
+ *
+ *  Copyright 2012 by Werner Almesberger
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <stdarg.h>
+#include <stdlib.h>
+
+#include "util.h"
+#include "param.h"
+#include "y.tab.h"
+
+
+static int lineno = 1;
+
+%}
+
+%%
+
+[-_A-Za-z0-9()+./]+		{ yylval.s = unique(yytext);
+				  return WORD; }
+
+"<="				return TOK_LE;
+">="				return TOK_GE;
+
+[ \t]				;
+\n				lineno++;
+^#[^n]*\n			lineno++;
+
+.				return *yytext;
+
+%%
+
+
+void yyerrorf(const char *fmt, ...)
+{
+	va_list ap;
+
+	va_start(ap, fmt);
+	fprintf(stderr, "%d: ", lineno);
+	vfprintf(stderr, fmt, ap) ;
+	fprintf(stderr, "\n");
+	va_end(ap);
+	exit(1);
+}
+
+
+void yyerror(const char *s)
+{
+	fprintf(stderr, "%d: %s\n", lineno, s);
+	exit(1);
+}
diff --git a/b2/lang.y b/b2/lang.y
new file mode 100644
index 0000000..3a0e15a
--- /dev/null
+++ b/b2/lang.y
@@ -0,0 +1,206 @@
+%{
+/* 
+ * lang.y - BOOM grammar
+ *
+ *  Copyright 2012 by Werner Almesberger
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+
+#include <stdlib.h>
+
+#include "util.h"
+#include "param.h"
+#include "chr.h"
+
+#include "y.tab.h"
+
+%}
+
+
+%union {
+	const char *s;
+	struct equiv *equiv;
+	struct names *names;
+	struct format *format;
+	enum relop relop;
+};
+
+
+%token			TOK_LE TOK_GE
+%token	<s>		WORD
+
+%type	<equiv>		nameqs
+%type	<names>		names nameq
+%type	<format>	format
+%type	<relop>		relop opt_relop
+
+%%
+
+all:
+	| nameset ';'
+	| rules
+	;
+
+nameset:
+	'<' WORD '>' '=' names ';'
+		{
+			register_nameset($2, $5);
+		}
+	;
+
+names:
+	nameq
+		{
+			$$ = $1;
+		}
+	| nameq '<' names
+		{
+			$$ = $1;
+			$$->next = $3;
+		}
+	;
+
+nameq:
+	nameqs
+		{
+			$$ = alloc_type(struct names);
+			$$->equiv = $1;
+			$$->next = NULL;
+		}
+	;
+
+nameqs:
+	WORD
+		{
+			$$ = alloc_type(struct equiv);
+			$$->name = $1;
+			$$->next = NULL;
+		}
+	| WORD '=' nameqs
+		{
+			$$ = alloc_type(struct equiv);
+			$$->name = $1;
+			$$->next = $3;
+		}
+	;
+
+rules:
+	field '{'
+		{
+			field_mark();
+		}
+	    selections opt_wildcard '}'
+		{
+			field_release();
+		}
+	;
+
+selections:
+	| selectors ':' opt_fields rules selections
+	;
+
+selectors:
+	selector
+	| selector '|'
+		{
+			field_more_selectors();
+		}
+	    selectors
+	;
+
+selector:
+	opt_relop WORD
+		{
+			field_add_selector($1, $2);
+		}
+	;
+
+opt_wildcard:
+	'*' ':'
+		{
+			field_add_wildcard();
+		}
+	;
+
+opt_relop:
+		{
+			$$ = rel_eq;
+		}
+	| relop
+		{
+			$$ = $1;
+		}
+	;
+
+relop:
+	'='
+		{
+			$$ = rel_eq;
+		}
+	| '<'
+		{
+			$$ = rel_le;
+		}
+	| '>'
+		{
+			$$ = rel_gt;
+		}
+	| TOK_LE
+		{
+			$$ = rel_le;
+		}
+	| TOK_GE
+		{
+			$$ = rel_ge;
+		}
+	;
+
+opt_fields:
+	| '{' fields '}'
+	;
+
+fields:
+	| field fields
+	;
+
+field:
+	WORD ':' format
+		{
+			field_add($1, $3);
+		}
+	;
+
+format:
+	'*'
+		{
+			$$ = alloc_type(struct format);
+			$$->ops = &param_ops_name;
+		}
+	| '<' WORD '>'
+		{
+			$$ = alloc_type(struct format);
+			$$->ops = &param_ops_set;
+			$$->u.set = find_nameset($2);
+			if (!$$->u.set)
+				yyerrorf("unknown name set \"%s\"", $2);
+		}
+	| '#' WORD
+		{
+			$$ = alloc_type(struct format);
+			$$->ops = &param_ops_abs;
+			$$->u.abs = $2;
+		}
+	| '%' WORD
+		{
+			$$ = alloc_type(struct format);
+			$$->ops = &param_ops_rel;
+			$$->u.rel = field_find($2);
+			if (!$$->u.rel)
+				yyerrorf("unknown field \"%s\"", $2);
+		}
+	;
diff --git a/b2/param.c b/b2/param.c
new file mode 100644
index 0000000..1e2a47c
--- /dev/null
+++ b/b2/param.c
@@ -0,0 +1,82 @@
+/*
+ * param.c - Parameters and values
+ *
+ * Copyright 2012 by Werner Almesberger
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+
+#include <glib.h>
+
+#include "util.h"
+#include "param.h"
+
+
+static GTree *tree;
+
+
+static int duplicate(const char *a, const struct equiv *b)
+{
+	while (b) {
+		if (a == b->name)
+			return 1;
+		b = b->next;
+	}
+	return 0;
+}
+
+
+static void check_duplicates(const struct names *n)
+{
+	const struct names *na, *nb;
+	const struct equiv *ea;
+
+	for (na = n; na; na = na->next) {
+		for (ea = na->equiv; ea; ea = ea->next)
+			if (duplicate(ea->name, ea->next))
+				yyerrorf("duplicate name \"%s\"", ea->name);
+		for (nb = na->next; nb; nb = nb->next)
+			if (duplicate(ea->name, nb->equiv))
+				yyerrorf("duplicate name \"%s\"", ea->name);
+	}
+}
+
+
+static gint comp(gconstpointer a, gconstpointer b)
+{
+	return a == b ? 0 : a < b ? -1 : 1;
+}
+
+
+void register_nameset(const char *name, const struct names *set)
+{
+	if (!tree)
+		tree = g_tree_new(comp);
+	if (g_tree_lookup(tree, name))
+		yyerrorf("duplicate name set \"%s\"", name);
+	check_duplicates(set);
+	g_tree_insert(tree, (void *) name, (void *) set);
+}
+
+
+const struct names *find_nameset(const char *name)
+{
+	return tree ? g_tree_lookup(tree, name) : NULL;
+}
+
+
+#define	MKOPS(type)					\
+	const struct param_ops param_ops_##type = {	\
+		.eval	= eval_##type,			\
+		.comp	= comp_##type,			\
+	}
+
+
+MKOPS(name);
+MKOPS(set);
+MKOPS(abs);
+MKOPS(rel);
diff --git a/b2/param.h b/b2/param.h
new file mode 100644
index 0000000..bc0753b
--- /dev/null
+++ b/b2/param.h
@@ -0,0 +1,99 @@
+/*
+ * param.h - Parameters and values
+ *
+ * Copyright 2012 by Werner Almesberger
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+
+#ifndef PARAM_H
+#define	PARAM_H
+
+#include "bitset.h"
+
+
+/*
+ * Parameter types:
+ *
+ * "name"	arbitrary name
+ * "set"	names from an ordered list
+ * "abs"	absolute numeric value
+ * "rel"	numeric value relative to another parameter
+ */
+
+
+enum relop {
+	rel_lt	= 1 << 0,
+	rel_le	= 1 << 1,
+	rel_eq	= 1 << 2,
+	rel_ge	= 1 << 3,
+	rel_gt	= 1 << 4,
+};
+
+struct equiv {
+	const char *name;
+	struct equiv *next;
+};
+
+struct names {
+	struct equiv *equiv;	/* equivalent value(s) */
+	struct names *next;	/* next/greater value */
+};
+
+struct param_ops;
+
+struct format {
+	const struct param_ops *ops;
+	union {
+		const struct names *set;
+		const char *abs;	/* unit name */
+		const struct format *rel;
+	} u;
+};
+
+struct value {
+	union {
+		const char *name;
+		struct bitset set;
+		double abs;
+		struct rel_value {
+			double plus, minus;
+			int fract;	/* 0: abs. offset; 1: fract. offs. */
+		} rel;
+	} u;
+};
+
+struct param_ops {
+	int (*eval)(const struct format *fmt, const char *s,
+	    struct value *res);
+	int (*comp)(const struct value *a, enum relop relop,
+	    const struct value *b);
+};
+
+
+void register_nameset(const char *name, const struct names *set);
+const struct names *find_nameset(const char *name);
+
+int eval_name(const struct format *fmt, const char *s, struct value *res);
+int eval_set(const struct format *fmt, const char *s, struct value *res);
+int eval_abs(const struct format *fmt, const char *s, struct value *res);
+int eval_rel(const struct format *fmt, const char *s, struct value *res);
+int evaluate(const struct format *fmt, const char *s, struct value *res);
+
+int comp_name(const struct value *a, enum relop relop, const struct value *b);
+int comp_set(const struct value *a, enum relop relop, const struct value *b);
+int comp_abs(const struct value *a, enum relop relop, const struct value *b);
+int comp_rel(const struct value *a, enum relop relop, const struct value *b);
+int compare(const struct format *fmt,
+    const struct value *a, enum relop relop, const struct value *b);
+
+extern const struct param_ops param_ops_name;
+extern const struct param_ops param_ops_set;
+extern const struct param_ops param_ops_abs;
+extern const struct param_ops param_ops_rel;
+
+#endif /* !PARAM_H */
diff --git a/b2/util.c b/b2/util.c
new file mode 100644
index 0000000..8b40791
--- /dev/null
+++ b/b2/util.c
@@ -0,0 +1,40 @@
+/*
+ * util.h - Utility functions
+ *
+ * Copyright 2012 by Werner Almesberger
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+
+#include <string.h>
+#include <glib.h>
+
+#include "util.h"
+
+
+static GTree *tree = NULL;
+
+
+static gint comp(gconstpointer a, gconstpointer b)
+{
+	return strcmp(a, b);
+}
+
+
+const char *unique(const char *s)
+{
+	char *u;
+
+	if (!tree)
+		tree = g_tree_new(comp);
+	u = g_tree_lookup(tree, s);
+	if (!u) {
+		u = strdup(s);
+		g_tree_insert(tree, u, u);
+	}
+	return u;
+}
diff --git a/b2/util.h b/b2/util.h
new file mode 100644
index 0000000..45ba2bf
--- /dev/null
+++ b/b2/util.h
@@ -0,0 +1,32 @@
+/*
+ * util.h - Utility functions
+ *
+ * Copyright 2012 by Werner Almesberger
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#ifndef	UTIL_H
+#define	UTIL_H
+
+#include <stdlib.h>
+
+
+#define alloc_size(s)				\
+    ({  void *alloc_size_tmp = malloc(s);	\
+	if (!alloc_size_tmp)			\
+		abort();			\
+	alloc_size_tmp; })
+
+#define alloc_type(t) ((t *) alloc_size(sizeof(t)))
+
+
+const char *unique(const char *s);
+
+void yyerrorf(const char *fmt, ...);
+void yyerror(const char *s);
+
+#endif /* !UTIL_H */