diff --git a/internal/grammar/path_test.go b/internal/grammar/path_test.go
index 6dad65e..47194a1 100644
--- a/internal/grammar/path_test.go
+++ b/internal/grammar/path_test.go
@@ -49,3 +49,11 @@ func TestCheckSegmentsRefusesAnEmptySegment(t *testing.T) {
 		t.Errorf("CheckSegments = %v, want nil", err)
 	}
 }
+
+func TestUnspellableInSelector(t *testing.T) {
+	for s, want := range map[string]string{"SE": "", "a|b": "|", `x"y[`: `"`, "": ""} {
+		if got := UnspellableInSelector(s); got != want {
+			t.Errorf("UnspellableInSelector(%q) = %q, want %q", s, got, want)
+		}
+	}
+}
diff --git a/pins.go b/pins.go
deleted file mode 100644
index d59e5fc..0000000
--- a/pins.go
+++ /dev/null
@@ -1,138 +0,0 @@
-package fejkdata
-
-import (
-	"fmt"
-
-	"github.com/larvit/fejkdata/internal/invariant"
-)
-
-type tablePin struct {
-	t   *table
-	row int
-}
-
-// pinSet is the table rows fixed so far.
-type pinSet struct {
-	inline [8]tablePin // sized so a render over a country's five-deep geo tree stays off the heap
-	used   int
-	spill  map[*table]int
-}
-
-func (p *pinSet) pinned(t *table) (int, bool) {
-	for _, q := range p.inline[:p.used] {
-		if q.t == t {
-			return q.row, true
-		}
-	}
-	r, ok := p.spill[t]
-	return r, ok
-}
-
-// mustRow is the row pinned for t, which the walk reaching a column pinned.
-func (p *pinSet) mustRow(t *table) int {
-	r, ok := p.pinned(t)
-	if !ok {
-		panic(invariant.Broken("a column of %s is rendered with no row pinned", t.segment))
-	}
-	return r
-}
-
-func (p *pinSet) add(t *table, r int) {
-	if p.used < len(p.inline) {
-		p.inline[p.used] = tablePin{t, r}
-		p.used++
-		return
-	}
-	if p.spill == nil {
-		p.spill = map[*table]int{}
-	}
-	p.spill[t] = r
-}
-
-// pin pins row r of t, and the rows of t's ancestors it links to. It checks nothing, so r must
-// agree with the row p pins of nearestPinned(t): ask clash first, as pinRow does, or draw r inside
-// it, as drawIn does.
-func (p *pinSet) pin(t *table, r int) {
-	for stop := p.nearestPinned(t); t != stop; t = t.parentT {
-		p.add(t, r)
-		if t.parentT != stop {
-			r = t.parentRow(r)
-		}
-	}
-}
-
-// nearestPinned is the first of t and its ancestors p pins, where pinning a row of t stops; nil
-// where none is.
-func (p *pinSet) nearestPinned(t *table) *table {
-	for ; t != nil; t = t.parentT {
-		if _, ok := p.pinned(t); ok {
-			return t
-		}
-	}
-	return nil
-}
-
-// clash is the table whose pinned row keeps row r of t out: t itself pinned to another row, or the
-// nearest ancestor pinned to a row r is not inside; nil where none does.
-func (p *pinSet) clash(t *table, r int) *table {
-	if pr, ok := p.pinned(t); ok && pr != r {
-		return t
-	}
-	for a := t.parentT; a != nil; a = a.parentT {
-		if pa, ok := p.pinned(a); ok && !t.under(r, a, pa) {
-			return a
-		}
-	}
-	return nil
-}
-
-// pinRow pins row r of t where it agrees with the rows pinned before it.
-func (p *pinSet) pinRow(t *table, r int) error {
-	switch a := p.clash(t, r); {
-	case a == t:
-		pr, _ := p.pinned(t)
-		return fmt.Errorf("%s and %s are two rows of %s", t.selectorSpelling(pr), t.selectorSpelling(r), t.path)
-	case a != nil:
-		pa, _ := p.pinned(a)
-		return fmt.Errorf("%s is not inside %s", t.selectorSpelling(r), a.selectorSpelling(pa))
-	}
-	p.pin(t, r)
-	return nil
-}
-
-func (p *pinSet) selectRow(t *table, sel string) error {
-	r, err := t.find(sel, p)
-	if err != nil {
-		return err
-	}
-	return p.pinRow(t, r)
-}
-
-// inside keeps the rows of t that sit inside every pinned ancestor.
-func (p *pinSet) inside(t *table, rows []int) []int {
-	for a := t.parentT; a != nil; a = a.parentT {
-		pa, ok := p.pinned(a)
-		if !ok {
-			continue
-		}
-		var kept []int
-		for _, r := range rows {
-			if t.under(r, a, pa) {
-				kept = append(kept, r)
-			}
-		}
-		rows = kept
-	}
-	return rows
-}
-
-// above is a pin set holding the rows p pins of t and its ancestors, and none below them.
-func (p *pinSet) above(t *table) *pinSet {
-	q := new(pinSet)
-	for ; t != nil; t = t.parentT {
-		if r, ok := p.pinned(t); ok {
-			q.add(t, r)
-		}
-	}
-	return q
-}