diff --git a/char.go b/char.go
index 3bb0ae6..24dfd9a 100644
--- a/char.go
+++ b/char.go
@@ -7,7 +7,7 @@ type charParser struct {
 	not        bool
 	chars      []rune
 	ranges     [][]rune
-	includedBy []parser
+	includedBy []int
 }
 
 func newChar(
@@ -30,6 +30,13 @@ func (p *charParser) nodeName() string { return p.name }
 func (p *charParser) nodeID() int      { return p.id }
 func (p *charParser) setID(id int)     { p.id = id }
 
+func (p *charParser) init(r *registry) error { return nil }
+
+func (p *charParser) setIncludedBy(r *registry, includedBy int, parsers *idSet) error {
+	p.includedBy = appendIfMissing(p.includedBy, includedBy)
+	return nil
+}
+
 func (p *charParser) parser(r *registry, parsers *idSet) (parser, error) {
 	if parsers.has(p.id) {
 		panic(cannotIncludeParsers(p.name))
@@ -47,14 +54,6 @@ func (p *charParser) commitType() CommitType {
 	return p.commit
 }
 
-func (p *charParser) setIncludedBy(includedBy parser, parsers *idSet) {
-	if parsers.has(p.id) {
-		panic(cannotIncludeParsers(p.name))
-	}
-
-	p.includedBy = append(p.includedBy, includedBy)
-}
-
 func (p *charParser) storeIncluded(*context, int, int) {
 	panic(cannotIncludeParsers(p.name))
 }
@@ -83,6 +82,6 @@ func (p *charParser) parse(t Trace, c *context) {
 
 	c.success(c.offset + 1)
 	for _, includedBy := range p.includedBy {
-		includedBy.storeIncluded(c, c.offset, c.offset+1)
+		c.store.setMatch(c.offset, includedBy, c.offset+1)
 	}
 }
diff --git a/choice.go b/choice.go
index 55df20b..a0f9ce0 100644
--- a/choice.go
+++ b/choice.go
@@ -1,10 +1,11 @@
 package treerack
 
 type choiceDefinition struct {
-	name     string
-	id       int
-	commit   CommitType
-	elements []string
+	name       string
+	id         int
+	commit     CommitType
+	elements   []string
+	includedBy []int
 }
 
 type choiceParser struct {
@@ -12,7 +13,7 @@ type choiceParser struct {
 	id         int
 	commit     CommitType
 	elements   []parser
-	includedBy []parser
+	includedBy []int
 }
 
 func newChoice(name string, ct CommitType, elements []string) *choiceDefinition {
@@ -27,6 +28,22 @@ func (d *choiceDefinition) nodeName() string { return d.name }
 func (d *choiceDefinition) nodeID() int      { return d.id }
 func (d *choiceDefinition) setID(id int)     { d.id = id }
 
+func (d *choiceDefinition) init(r *registry) error {
+	parsers := &idSet{}
+	parsers.set(d.id)
+	return setItemsIncludedBy(r, d.elements, d.id, parsers)
+}
+
+func (d *choiceDefinition) setIncludedBy(r *registry, includedBy int, parsers *idSet) error {
+	if parsers.has(d.id) {
+		return nil
+	}
+
+	d.includedBy = appendIfMissing(d.includedBy, includedBy)
+	parsers.set(d.id)
+	return setItemsIncludedBy(r, d.elements, includedBy, parsers)
+}
+
 func (d *choiceDefinition) parser(r *registry, parsers *idSet) (parser, error) {
 	p, ok := r.parser(d.name)
 	if ok {
@@ -34,9 +51,10 @@ func (d *choiceDefinition) parser(r *registry, parsers *idSet) (parser, error) {
 	}
 
 	cp := &choiceParser{
-		name:   d.name,
-		id:     d.id,
-		commit: d.commit,
+		name:       d.name,
+		id:         d.id,
+		commit:     d.commit,
+		includedBy: d.includedBy,
 	}
 
 	r.setParser(cp)
@@ -48,7 +66,6 @@ func (d *choiceDefinition) parser(r *registry, parsers *idSet) (parser, error) {
 		element, ok := r.parser(e)
 		if ok {
 			elements = append(elements, element)
-			element.setIncludedBy(cp, parsers)
 			continue
 		}
 
@@ -62,7 +79,6 @@ func (d *choiceDefinition) parser(r *registry, parsers *idSet) (parser, error) {
 			return nil, err
 		}
 
-		element.setIncludedBy(cp, parsers)
 		elements = append(elements, element)
 	}
 
@@ -77,26 +93,6 @@ func (d *choiceDefinition) commitType() CommitType {
 func (p *choiceParser) nodeName() string { return p.name }
 func (p *choiceParser) nodeID() int      { return p.id }
 
-func (p *choiceParser) setIncludedBy(includedBy parser, parsers *idSet) {
-	if parsers.has(p.id) {
-		return
-	}
-
-	p.includedBy = append(p.includedBy, includedBy)
-}
-
-func (p *choiceParser) storeIncluded(c *context, from, to int) {
-	if !c.excluded(from, p.id) {
-		return
-	}
-
-	c.store.setMatch(from, p.id, to)
-
-	for _, includedBy := range p.includedBy {
-		includedBy.storeIncluded(c, from, to)
-	}
-}
-
 func (p *choiceParser) parse(t Trace, c *context) {
 	if p.commit&Documentation != 0 {
 		c.fail(c.offset)
@@ -140,7 +136,7 @@ func (p *choiceParser) parse(t Trace, c *context) {
 
 			c.store.setMatch(from, p.id, to)
 			for _, includedBy := range p.includedBy {
-				includedBy.storeIncluded(c, from, to)
+				c.store.setMatch(from, includedBy, to)
 			}
 		}
 
diff --git a/parse.go b/parse.go
index 91bb52d..d7d859d 100644
--- a/parse.go
+++ b/parse.go
@@ -6,6 +6,8 @@ type definition interface {
 	nodeName() string
 	nodeID() int
 	setID(int)
+	init(*registry) error
+	setIncludedBy(*registry, int, *idSet) error
 	parser(*registry, *idSet) (parser, error)
 	commitType() CommitType
 	// builder() builder
@@ -14,8 +16,6 @@ type definition interface {
 type parser interface {
 	nodeName() string
 	nodeID() int
-	setIncludedBy(parser, *idSet)
-	storeIncluded(*context, int, int) // can be just an id set, taking what's excluded from the context
 	parse(Trace, *context)
 }
 
@@ -33,6 +33,46 @@ func cannotIncludeParsers(name string) error {
 	return fmt.Errorf("parser: %s cannot include other parsers", name)
 }
 
+func intsContain(is []int, i int) bool {
+	for _, ii := range is {
+		if ii == i {
+			return true
+		}
+	}
+
+	return false
+}
+
+func appendIfMissing(is []int, i int) []int {
+	if intsContain(is, i) {
+		return is
+	}
+
+	return append(is, i)
+}
+
+func setItemsIncludedBy(r *registry, items []string, includedBy int, parsers *idSet) error {
+	for _, item := range items {
+		di, ok := r.definition(item)
+		if !ok {
+			return ErrNoParsersDefined
+		}
+
+		di.setIncludedBy(r, includedBy, parsers)
+	}
+
+	return nil
+}
+
+func sequenceItemNames(items []SequenceItem) []string {
+	names := make([]string, len(items))
+	for i := range items {
+		names[i] = items[i].Name
+	}
+
+	return names
+}
+
 func parse(t Trace, p parser, c *context) (*Node, error) {
 	p.parse(t, c)
 	if c.readErr != nil {
diff --git a/sequence.go b/sequence.go
index eecaa1d..c30582a 100644
--- a/sequence.go
+++ b/sequence.go
@@ -1,10 +1,11 @@
 package treerack
 
 type sequenceDefinition struct {
-	name   string
-	id     int
-	commit CommitType
-	items  []SequenceItem
+	name       string
+	id         int
+	commit     CommitType
+	items      []SequenceItem
+	includedBy []int
 }
 
 type sequenceParser struct {
@@ -13,7 +14,7 @@ type sequenceParser struct {
 	commit     CommitType
 	items      []parser
 	ranges     [][]int
-	includedBy []parser
+	includedBy []int
 }
 
 func newSequence(name string, ct CommitType, items []SequenceItem) *sequenceDefinition {
@@ -28,6 +29,42 @@ func (d *sequenceDefinition) nodeName() string { return d.name }
 func (d *sequenceDefinition) nodeID() int      { return d.id }
 func (d *sequenceDefinition) setID(id int)     { d.id = id }
 
+func (d *sequenceDefinition) includeItems() bool {
+	return len(d.items) == 1 && d.items[0].Min == 1 && d.items[0].Max == 1
+}
+
+func (d *sequenceDefinition) init(r *registry) error {
+	for _, item := range d.items {
+		if item.Min == 0 && item.Max == 0 {
+			item.Min, item.Max = 1, 1
+		} else if item.Max == 0 {
+			item.Max = -1
+		}
+	}
+
+	if !d.includeItems() {
+		return nil
+	}
+
+	parsers := &idSet{}
+	parsers.set(d.id)
+	return setItemsIncludedBy(r, sequenceItemNames(d.items), d.id, parsers)
+}
+
+func (d *sequenceDefinition) setIncludedBy(r *registry, includedBy int, parsers *idSet) error {
+	if parsers.has(d.id) {
+		return nil
+	}
+
+	d.includedBy = appendIfMissing(d.includedBy, includedBy)
+	if !d.includeItems() {
+		return nil
+	}
+
+	parsers.set(d.id)
+	return setItemsIncludedBy(r, sequenceItemNames(d.items), includedBy, parsers)
+}
+
 func (d *sequenceDefinition) parser(r *registry, parsers *idSet) (parser, error) {
 	if parsers.has(d.id) {
 		panic(cannotIncludeParsers(d.name))
@@ -39,9 +76,10 @@ func (d *sequenceDefinition) parser(r *registry, parsers *idSet) (parser, error)
 	}
 
 	sp := &sequenceParser{
-		name:   d.name,
-		id:     d.id,
-		commit: d.commit,
+		name:       d.name,
+		id:         d.id,
+		commit:     d.commit,
+		includedBy: d.includedBy,
 	}
 
 	r.setParser(sp)
@@ -81,11 +119,6 @@ func (d *sequenceDefinition) parser(r *registry, parsers *idSet) (parser, error)
 		ranges = append(ranges, []int{item.Min, item.Max})
 	}
 
-	// for single items, acts like a choice
-	if len(items) == 1 && ranges[0][0] == 1 && ranges[0][1] == 1 {
-		items[0].setIncludedBy(sp, parsers)
-	}
-
 	sp.items = items
 	sp.ranges = ranges
 	return sp, nil
@@ -98,26 +131,6 @@ func (d *sequenceDefinition) commitType() CommitType {
 func (p *sequenceParser) nodeName() string { return p.name }
 func (p *sequenceParser) nodeID() int      { return p.id }
 
-func (p *sequenceParser) setIncludedBy(includedBy parser, parsers *idSet) {
-	if parsers.has(p.id) {
-		return
-	}
-
-	p.includedBy = append(p.includedBy, includedBy)
-}
-
-func (p *sequenceParser) storeIncluded(c *context, from, to int) {
-	if !c.excluded(from, p.id) {
-		return
-	}
-
-	c.store.setMatch(from, p.id, to)
-
-	for _, includedBy := range p.includedBy {
-		includedBy.storeIncluded(c, from, to)
-	}
-}
-
 func (p *sequenceParser) parse(t Trace, c *context) {
 	if p.commit&Documentation != 0 {
 		c.fail(c.offset)
@@ -169,7 +182,7 @@ func (p *sequenceParser) parse(t Trace, c *context) {
 	}
 
 	for _, includedBy := range p.includedBy {
-		includedBy.storeIncluded(c, from, to)
+		c.store.setMatch(from, includedBy, to)
 	}
 
 	c.store.setMatch(from, p.id, to)
diff --git a/syntax.go b/syntax.go
index 22cef17..424b6b3 100644
--- a/syntax.go
+++ b/syntax.go
@@ -143,6 +143,10 @@ func (s *Syntax) Init() error {
 		return ErrRootAlias
 	}
 
+	for _, p := range s.registry.definitions {
+		p.init(s.registry)
+	}
+
 	var err error
 	s.parser, err = s.root.parser(s.registry, &idSet{})
 	if err != nil {