diff --git a/src/pkg/exp/locale/collate/build/colelem.go b/src/pkg/exp/locale/collate/build/colelem.go
new file mode 100644
index 0000000000..09425320fd
--- /dev/null
+++ b/src/pkg/exp/locale/collate/build/colelem.go
@@ -0,0 +1,179 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package build
+
+import (
+	"fmt"
+	"unicode"
+)
+
+const (
+	defaultSecondary = 0x20
+	defaultTertiary  = 0x2
+	maxTertiary      = 0x1F
+)
+
+// A collation element is represented as an uint32.
+// In the typical case, a rune maps to a single collation element. If a rune
+// can be the start of a contraction or expands into multiple collation elements,
+// then the collation element that is associated with a rune will have a special
+// form to represent such m to n mappings.  Such special collation elements
+// have a value >= 0x80000000.
+
+// For normal collation elements, we assume that a collation element either has
+// a primary or non-default secondary value, not both.
+// Collation elements with a primary value are of the form
+// 010ppppp pppppppp pppppppp tttttttt, where
+//   - p* is primary collation value
+//   - t* is the tertiary collation value
+// Collation elements with a secondary value are of the form
+// 00000000 ssssssss ssssssss tttttttt, where
+//   - s* is the secondary collation value
+//   - t* is the tertiary collation value
+const (
+	maxPrimaryBits   = 21
+	maxSecondaryBits = 16
+	maxTertiaryBits  = 8
+
+	isPrimary = 0x40000000
+)
+
+func makeCE(weights []int) (uint32, error) {
+	if w := weights[0]; w >= 1<<maxPrimaryBits || w < 0 {
+		return 0, fmt.Errorf("makeCE: primary weight out of bounds: %x >= %x", w, 1<<maxPrimaryBits)
+	}
+	if w := weights[1]; w >= 1<<maxSecondaryBits || w < 0 {
+		return 0, fmt.Errorf("makeCE: secondary weight out of bounds: %x >= %x", w, 1<<maxSecondaryBits)
+	}
+	if w := weights[2]; w >= 1<<maxTertiaryBits || w < 0 {
+		return 0, fmt.Errorf("makeCE: tertiary weight out of bounds: %d >= %d", w, 1<<maxTertiaryBits)
+	}
+	ce := uint32(0)
+	if weights[0] != 0 {
+		// primary weight form
+		if weights[1] != defaultSecondary {
+			return 0, fmt.Errorf("makeCE: non-default secondary weight for non-zero primary: %X", weights)
+		}
+		ce = uint32(weights[0]<<maxTertiaryBits + weights[2])
+		ce |= isPrimary
+	} else {
+		// secondary weight form
+		ce = uint32(weights[1]<<maxTertiaryBits + weights[2])
+	}
+	return ce, nil
+}
+
+// For contractions, collation elements are of the form
+// 10bbbbbb bbbbbbbb iiiiiiii iiinnnnn, where
+//   - n* is the size of the first node in the contraction trie.
+//   - i* is the index of the first node in the contraction trie.
+//   - b* is the offset into the contraction collation element table.
+// See contract.go for details on the contraction trie.
+const (
+	contractID            = 0x80000000
+	maxNBits              = 5
+	maxTrieIndexBits      = 11
+	maxContractOffsetBits = 14
+)
+
+func makeContractIndex(h ctHandle, offset int) (uint32, error) {
+	if h.n >= 1<<maxNBits {
+		return 0, fmt.Errorf("size of contraction trie node too large: %d >= %d", h.n, 1<<maxNBits)
+	}
+	if h.index >= 1<<maxTrieIndexBits {
+		return 0, fmt.Errorf("size of contraction trie offset too large: %d >= %d", h.index, 1<<maxTrieIndexBits)
+	}
+	if offset >= 1<<maxContractOffsetBits {
+		return 0, fmt.Errorf("offset out of bounds: %x >= %x", offset, 1<<maxContractOffsetBits)
+	}
+	ce := uint32(contractID)
+	ce += uint32(offset << (maxTrieIndexBits + maxNBits))
+	ce += uint32(h.index << maxNBits)
+	ce += uint32(h.n)
+	return ce, nil
+}
+
+// For expansions, collation elements are of the form
+// 110bbbbb bbbbbbbb bbbbbbbb bbbbbbbb,
+// where b* is the index into the expansion sequence table.
+const (
+	expandID           = 0xC0000000
+	maxExpandIndexBits = 29
+)
+
+func makeExpandIndex(index int) (uint32, error) {
+	if index >= 1<<maxExpandIndexBits {
+		return 0, fmt.Errorf("index out of bounds: %x >= %x", index, 1<<maxExpandIndexBits)
+	}
+	return expandID + uint32(index), nil
+}
+
+// Each list of collation elements corresponding to an expansion starts with 
+// a header indicating the length of the sequence.
+func makeExpansionHeader(n int) (uint32, error) {
+	return uint32(n), nil
+}
+
+// Some runes can be expanded using NFKD decomposition. Instead of storing the full
+// sequence of collation elements, we decompose the rune and lookup the collation
+// elements for each rune in the decomposition and modify the tertiary weights.
+// The collation element, in this case, is of the form
+// 11100000 00000000 wwwwwwww vvvvvvvv, where
+//   - v* is the replacement tertiary weight for the first rune,
+//   - w* is the replacement tertiary weight for the second rune,
+// Tertiary weights of subsequent runes should be replaced with maxTertiary.
+// See http://www.unicode.org/reports/tr10/#Compatibility_Decompositions for more details.
+const (
+	decompID = 0xE0000000
+)
+
+func makeDecompose(t1, t2 int) (uint32, error) {
+	if t1 >= 256 || t1 < 0 {
+		return 0, fmt.Errorf("first tertiary weight out of bounds: %d >= 256", t1)
+	}
+	if t2 >= 256 || t2 < 0 {
+		return 0, fmt.Errorf("second tertiary weight out of bounds: %d >= 256", t2)
+	}
+	return uint32(t2<<8+t1) + decompID, nil
+}
+
+const (
+	// These constants were taken from http://www.unicode.org/versions/Unicode6.0.0/ch12.pdf.
+	minUnified       rune = 0x4E00
+	maxUnified            = 0x9FFF
+	minCompatibility      = 0xF900
+	maxCompatibility      = 0xFAFF
+	minRare               = 0x3400
+	maxRare               = 0x4DBF
+)
+const (
+	commonUnifiedOffset = 0xFB40
+	rareUnifiedOffset   = 0x1FB40
+	otherOffset         = 0x4FB40
+	illegalOffset       = otherOffset + unicode.MaxRune
+	maxPrimary          = illegalOffset + 2 // there are 2 illegal values.
+)
+
+// implicitPrimary returns the primary weight for the a rune
+// for which there is no entry for the rune in the collation table.
+// We take a different approach from the one specified in
+// http://unicode.org/reports/tr10/#Implicit_Weights,
+// but preserve the resulting relative ordering of the runes.
+func implicitPrimary(r rune) int {
+
+	if r >= minUnified && r <= maxUnified {
+		// The most common case for CJK.
+		return int(r) + commonUnifiedOffset
+	}
+	if r >= minCompatibility && r <= maxCompatibility {
+		// This will never hit as long as we don't remove the characters
+		// that would match from the table.
+		return int(r) + commonUnifiedOffset
+	}
+	if unicode.Is(unicode.Unified_Ideograph, r) {
+		return int(r) + rareUnifiedOffset
+	}
+	return int(r) + otherOffset
+}
diff --git a/src/pkg/exp/locale/collate/build/colelem_test.go b/src/pkg/exp/locale/collate/build/colelem_test.go
new file mode 100644
index 0000000000..841ac11629
--- /dev/null
+++ b/src/pkg/exp/locale/collate/build/colelem_test.go
@@ -0,0 +1,80 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package build
+
+import "testing"
+
+type ceTest struct {
+	f   func(in []int) (uint32, error)
+	arg []int
+	val uint32
+}
+
+func normalCE(in []int) (ce uint32, err error) {
+	return makeCE(in)
+}
+
+func expandCE(in []int) (ce uint32, err error) {
+	return makeExpandIndex(in[0])
+}
+
+func contractCE(in []int) (ce uint32, err error) {
+	return makeContractIndex(ctHandle{in[0], in[1]}, in[2])
+}
+
+func decompCE(in []int) (ce uint32, err error) {
+	return makeDecompose(in[0], in[1])
+}
+
+var ceTests = []ceTest{
+	{normalCE, []int{0, 0, 0}, 000},
+	{normalCE, []int{0, 30, 3}, 0x1E03},
+	{normalCE, []int{100, defaultSecondary, 3}, 0x40006403},
+	{normalCE, []int{100, 0, 3}, 0xFFFF}, // non-ignorable primary with non-default secondary
+	{normalCE, []int{100, 1, 3}, 0xFFFF},
+	{normalCE, []int{1 << maxPrimaryBits, defaultSecondary, 0}, 0xFFFF},
+	{normalCE, []int{0, 1 << maxSecondaryBits, 0}, 0xFFFF},
+	{normalCE, []int{100, defaultSecondary, 1 << maxTertiaryBits}, 0xFFFF},
+
+	{contractCE, []int{0, 0, 0}, 0x80000000},
+	{contractCE, []int{1, 1, 1}, 0x80010021},
+	{contractCE, []int{1, (1 << maxNBits) - 1, 1}, 0x8001003F},
+	{contractCE, []int{(1 << maxTrieIndexBits) - 1, 1, 1}, 0x8001FFE1},
+	{contractCE, []int{1, 1, (1 << maxContractOffsetBits) - 1}, 0xBFFF0021},
+	{contractCE, []int{1, (1 << maxNBits), 1}, 0xFFFF},
+	{contractCE, []int{(1 << maxTrieIndexBits), 1, 1}, 0xFFFF},
+	{contractCE, []int{1, (1 << maxContractOffsetBits), 1}, 0xFFFF},
+
+	{expandCE, []int{0}, 0xC0000000},
+	{expandCE, []int{5}, 0xC0000005},
+	{expandCE, []int{(1 << maxExpandIndexBits) - 1}, 0xDFFFFFFF},
+	{expandCE, []int{1 << maxExpandIndexBits}, 0xFFFF},
+
+	{decompCE, []int{0, 0}, 0xE0000000},
+	{decompCE, []int{1, 1}, 0xE0000101},
+	{decompCE, []int{0x1F, 0x1F}, 0xE0001F1F},
+	{decompCE, []int{256, 0x1F}, 0xFFFF},
+	{decompCE, []int{0x1F, 256}, 0xFFFF},
+}
+
+func TestColElem(t *testing.T) {
+	for i, tt := range ceTests {
+		in := make([]int, len(tt.arg))
+		copy(in, tt.arg)
+		ce, err := tt.f(in)
+		if tt.val == 0xFFFF {
+			if err == nil {
+				t.Errorf("%d: expected error for args %x", i, tt.arg)
+			}
+			continue
+		}
+		if err != nil {
+			t.Errorf("%d: unexpected error: %v", i, err.Error())
+		}
+		if ce != tt.val {
+			t.Errorf("%d: colElem=%X; want %X", i, ce, tt.val)
+		}
+	}
+}
diff --git a/src/pkg/exp/locale/collate/colelem.go b/src/pkg/exp/locale/collate/colelem.go
new file mode 100644
index 0000000000..03cfc678e8
--- /dev/null
+++ b/src/pkg/exp/locale/collate/colelem.go
@@ -0,0 +1,170 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package collate
+
+import (
+	"unicode"
+)
+
+// weights holds the decoded weights per collation level.
+type weights struct {
+	primary   uint32
+	secondary uint16
+	tertiary  uint8
+	// TODO: compute quaternary on the fly or compress this value into 8 bits
+	// such that weights fit within 64bit.
+	quaternary uint32
+}
+
+const (
+	defaultSecondary = 0x20
+	defaultTertiary  = 0x2
+	maxTertiary      = 0x1F
+)
+
+// colElem is a representation of a collation element.
+// In the typical case, a rune maps to a single collation element. If a rune
+// can be the start of a contraction or expands into multiple collation elements,
+// then the colElem that is associated with a rune will have a special form to represent
+// such m to n mappings.  Such special colElems have a value >= 0x80000000.
+type colElem uint32
+
+const (
+	maxCE       colElem = 0x7FFFFFFF
+	minContract         = 0x80000000
+	maxContract         = 0xBFFFFFFF
+	minExpand           = 0xC0000000
+	maxExpand           = 0xDFFFFFFF
+	minDecomp           = 0xE0000000
+)
+
+type ceType int
+
+const (
+	ceNormal           ceType = iota // ceNormal includes implicits (ce == 0)
+	ceContractionIndex               // rune can be a start of a contraction
+	ceExpansionIndex                 // rune expands into a sequence of collation elements
+	ceDecompose                      // rune expands using NFKC decomposition
+)
+
+func (ce colElem) ctype() ceType {
+	if ce <= maxCE {
+		return ceNormal
+	}
+	if ce <= maxContract {
+		return ceContractionIndex
+	} else {
+		if ce <= maxExpand {
+			return ceExpansionIndex
+		}
+		return ceDecompose
+	}
+	panic("should not reach here")
+	return ceType(-1)
+}
+
+// For normal collation elements, we assume that a collation element either has
+// a primary or non-default secondary value, not both.
+// Collation elements with a primary value are of the form
+// 010ppppp pppppppp pppppppp tttttttt, where
+//   - p* is primary collation value
+//   - t* is the tertiary collation value
+// Collation elements with a secondary value are of the form
+// 00000000 ssssssss ssssssss tttttttt, where
+//   - s* is the secondary collation value
+//   - t* is the tertiary collation value
+func splitCE(ce colElem) weights {
+	w := weights{}
+	w.tertiary = uint8(ce)
+	if ce&0x40000000 != 0 {
+		// primary weight form
+		w.primary = uint32((ce >> 8) & 0x1FFFFF)
+		w.secondary = defaultSecondary
+	} else {
+		// secondary weight form
+		w.secondary = uint16(ce >> 8)
+	}
+	return w
+}
+
+// For contractions, colElems are of the form 10bbbbbb bbbbbbbb hhhhhhhh hhhhhhhh, where
+//   - h* is the compTrieHandle.
+//   - b* is the offset into the contraction collation element table.
+// See contract.go for details on the contraction trie.
+const (
+	maxNBits              = 5
+	maxTrieIndexBits      = 11
+	maxContractOffsetBits = 14
+)
+
+func splitContractIndex(ce colElem) (index, n, offset int) {
+	h := uint16(ce)
+	return int(h >> maxNBits), int(h & (1<<maxNBits - 1)), int(ce>>16) & (1<<maxContractOffsetBits - 1)
+}
+
+// For expansions, colElems are of the form 110bbbbb bbbbbbbb bbbbbbbb bbbbbbbb,
+// where b* is the index into the expansion sequence table.
+const (
+	maxExpandIndexBits = 29
+)
+
+func splitExpandIndex(ce colElem) (index int) {
+	index = int(ce) & (1<<maxExpandIndexBits - 1)
+	return
+}
+
+// Some runes can be expanded using NFKD decomposition. Instead of storing the full
+// sequence of collation elements, we decompose the rune and lookup the collation
+// elements for each rune in the decomposition and modify the tertiary weights.
+// The colElem, in this case, is of the form 11100000 00000000 wwwwwwww vvvvvvvv, where
+//   - v* is the replacement tertiary weight for the first rune,
+//   - w* is the replacement tertiary weight for the second rune,
+// Tertiary weights of subsequent runes should be replaced with maxTertiary.
+// See http://www.unicode.org/reports/tr10/#Compatibility_Decompositions for more details.
+const (
+	decompID = 0xE0000000
+)
+
+func splitDecompose(ce colElem) (t1, t2 uint8) {
+	return uint8(ce), uint8(ce >> 8)
+}
+
+const (
+	// These constants were taken from http://www.unicode.org/versions/Unicode6.0.0/ch12.pdf.
+	minUnified       rune = 0x4E00
+	maxUnified            = 0x9FFF
+	minCompatibility      = 0xF900
+	maxCompatibility      = 0xFAFF
+	minRare               = 0x3400
+	maxRare               = 0x4DBF
+)
+const (
+	commonUnifiedOffset = 0xFB40
+	rareUnifiedOffset   = 0x1FB40
+	otherOffset         = 0x4FB40
+	maxPrimary          = otherOffset + unicode.MaxRune
+)
+
+// implicitPrimary returns the primary weight for the a rune
+// for which there is no entry for the rune in the collation table.
+// We take a different approach from the one specified in
+// http://unicode.org/reports/tr10/#Implicit_Weights,
+// but preserve the resulting relative ordering of the runes.
+func implicitPrimary(r rune) int {
+
+	if r >= minUnified && r <= maxUnified {
+		// The most common case for CJK.
+		return int(r) + commonUnifiedOffset
+	}
+	if r >= minCompatibility && r <= maxCompatibility {
+		// This will never hit as long as we don't remove the characters
+		// that would match from the table.
+		return int(r) + commonUnifiedOffset
+	}
+	if unicode.Is(unicode.Unified_Ideograph, r) {
+		return int(r) + rareUnifiedOffset
+	}
+	return int(r) + otherOffset
+}
diff --git a/src/pkg/exp/locale/collate/colelem_test.go b/src/pkg/exp/locale/collate/colelem_test.go
new file mode 100644
index 0000000000..b201f81457
--- /dev/null
+++ b/src/pkg/exp/locale/collate/colelem_test.go
@@ -0,0 +1,157 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package collate
+
+import (
+	"testing"
+	"unicode"
+)
+
+type ceTest struct {
+	f   func(inout []int) (colElem, ceType)
+	arg []int
+}
+
+// The make* funcs are simplified versions of the functions in build/colelem.go
+func makeCE(weights []int) colElem {
+	const (
+		maxPrimaryBits   = 21
+		maxSecondaryBits = 16
+		maxTertiaryBits  = 8
+		isPrimary        = 0x40000000
+	)
+	var ce colElem
+	if weights[0] != 0 {
+		ce = colElem(weights[0]<<maxTertiaryBits + weights[2])
+		ce |= isPrimary
+	} else {
+		ce = colElem(weights[1]<<maxTertiaryBits + weights[2])
+	}
+	return ce
+}
+
+func makeContractIndex(index, n, offset int) colElem {
+	const (
+		contractID       = 0x80000000
+		maxNBits         = 5
+		maxTrieIndexBits = 11
+	)
+	ce := colElem(contractID)
+	ce += colElem(offset << (maxTrieIndexBits + maxNBits))
+	ce += colElem(index << maxNBits)
+	ce += colElem(n)
+	return ce
+}
+
+func makeExpandIndex(index int) colElem {
+	const expandID = 0xC0000000
+	return expandID + colElem(index)
+}
+
+func makeDecompose(t1, t2 int) colElem {
+	const decompID = 0xE0000000
+	return colElem(t2<<8+t1) + decompID
+}
+
+func normalCE(inout []int) (ce colElem, t ceType) {
+	w := splitCE(makeCE(inout))
+	inout[0] = int(w.primary)
+	inout[1] = int(w.secondary)
+	inout[2] = int(w.tertiary)
+	return ce, ceNormal
+}
+
+func expandCE(inout []int) (ce colElem, t ceType) {
+	ce = makeExpandIndex(inout[0])
+	inout[0] = splitExpandIndex(ce)
+	return ce, ceExpansionIndex
+}
+
+func contractCE(inout []int) (ce colElem, t ceType) {
+	ce = makeContractIndex(inout[0], inout[1], inout[2])
+	i, n, o := splitContractIndex(ce)
+	inout[0], inout[1], inout[2] = i, n, o
+	return ce, ceContractionIndex
+}
+
+func decompCE(inout []int) (ce colElem, t ceType) {
+	ce = makeDecompose(inout[0], inout[1])
+	t1, t2 := splitDecompose(ce)
+	inout[0], inout[1] = int(t1), int(t2)
+	return ce, ceDecompose
+}
+
+const (
+	maxPrimaryBits   = 21
+	maxSecondaryBits = 16
+	maxTertiaryBits  = 8
+)
+
+var ceTests = []ceTest{
+	{normalCE, []int{0, 0, 0}},
+	{normalCE, []int{0, 30, 3}},
+	{normalCE, []int{100, defaultSecondary, 3}},
+
+	{contractCE, []int{0, 0, 0}},
+	{contractCE, []int{1, 1, 1}},
+	{contractCE, []int{1, (1 << maxNBits) - 1, 1}},
+	{contractCE, []int{(1 << maxTrieIndexBits) - 1, 1, 1}},
+	{contractCE, []int{1, 1, (1 << maxContractOffsetBits) - 1}},
+
+	{expandCE, []int{0}},
+	{expandCE, []int{5}},
+	{expandCE, []int{(1 << maxExpandIndexBits) - 1}},
+
+	{decompCE, []int{0, 0}},
+	{decompCE, []int{1, 1}},
+	{decompCE, []int{0x1F, 0x1F}},
+}
+
+func TestColElem(t *testing.T) {
+	for i, tt := range ceTests {
+		inout := make([]int, len(tt.arg))
+		copy(inout, tt.arg)
+		ce, typ := tt.f(inout)
+		if ce.ctype() != typ {
+			t.Errorf("%d: type is %d; want %d", i, ce.ctype(), typ)
+		}
+		for j, a := range tt.arg {
+			if inout[j] != a {
+				t.Errorf("%d: argument %d is %d; want %d", i, j, inout[j], a)
+			}
+		}
+	}
+}
+
+type implicitTest struct {
+	r rune
+	p int
+}
+
+var implicitTests = []implicitTest{
+	{0x33FF, 0x52F3F},
+	{0x3400, 0x22F40},
+	{0x4DC0, 0x54900},
+	{0x4DFF, 0x5493F},
+	{0x4E00, 0x14940},
+	{0x9FCB, 0x19B0B},
+	{0xA000, 0x59B40},
+	{0xF8FF, 0x5F43F},
+	{0xF900, 0x1F440},
+	{0xFA23, 0x1F563},
+	{0xFAFF, 0x1F63F},
+	{0xFB00, 0x5F640},
+	{0x20000, 0x3FB40},
+	{0x2B81C, 0x4B35C},
+	{unicode.MaxRune, 0x15FB3F}, // maximum primary value
+}
+
+func TestImplicit(t *testing.T) {
+	for _, tt := range implicitTests {
+		if p := implicitPrimary(tt.r); p != tt.p {
+			t.Errorf("%U: was %X; want %X", tt.r, p, tt.p)
+		}
+	}
+}