diff --git a/cmd/gotime-cui/gotime-cui b/cmd/gotime-cui/gotime-cui
index eb582a7..49e53a9 100755
Binary files a/cmd/gotime-cui/gotime-cui and b/cmd/gotime-cui/gotime-cui differ
diff --git a/cmd/gotime-cui/main.go b/cmd/gotime-cui/main.go
index be1939d..9d42a36 100644
--- a/cmd/gotime-cui/main.go
+++ b/cmd/gotime-cui/main.go
@@ -3,12 +3,12 @@ package main
 import (
 	"fmt"
 	"os"
+	"strconv"
 
 	"gogs.bullercodeworks.com/brian/gotime"
 )
 
 func main() {
-	var dir string
 	/*
 		err := termbox.Init()
 		if err != nil {
@@ -16,23 +16,38 @@ func main() {
 		}
 		defer termbox.Close()
 	*/
+	dir := "/home/brbuller/.timewarrior/"
 
-	if len(os.Args) > 1 {
-		dir = os.Args[1]
+	op := os.Args[1]
+	var id int
+	var err error
+
+	if len(os.Args) > 2 {
+		id, err = strconv.Atoi(os.Args[2])
+		if err != nil {
+			panic(err)
+		}
 	}
+
 	got := gotime.Create(dir)
-	t := got.GetAllTimers()
-	for i := range t {
-		fmt.Println(t[i].ToJsonString())
-	}
-	fmt.Println("=== Start Timer ===")
-	ts := gotime.CreateStartTimerTxns(&t[len(t)-1])
-	for i := range ts {
-		fmt.Println(ts[i].ToString())
-	}
-	fmt.Println("=== Stop Timer ===")
-	ts = gotime.CreateStopTimerTxns(&t[len(t)-1])
-	for i := range ts {
-		fmt.Println(ts[i].ToString())
+
+	switch op {
+	case "ls":
+		tmrs := got.GetAllTimers()
+		for i := range tmrs {
+			fmt.Println("@" + strconv.Itoa(tmrs[i].Id) + ": " + tmrs[i].ToString())
+		}
+	case "tag":
+		if _, err := got.AddTagsToTimer(id, os.Args[3:]); err != nil {
+			panic(err)
+		}
+	case "untag":
+		if _, err := got.RemoveTagsFromTimer(id, os.Args[3:]); err != nil {
+			panic(err)
+		}
+	case "start":
+		got.StartTimer()
+	case "stop":
+		got.StopTimer()
 	}
 }
diff --git a/gotime.go b/gotime.go
index a5b8505..6392f9a 100644
--- a/gotime.go
+++ b/gotime.go
@@ -1,18 +1,22 @@
 package gotime
 
 import (
+	"errors"
 	"fmt"
+	"io"
 	"io/ioutil"
+	"os"
 	"strings"
 	"time"
 )
 
 type GoTime struct {
-	Dir        string
-	timers     []Timer
-	files      []string
-	timeFormat string
-	Tags       []string
+	Dir          string
+	timers       []Timer
+	files        []string
+	timeFormat   string
+	Tags         []string
+	CurrDataFile string
 }
 
 // Create creates a new instance of GoTime
@@ -21,6 +25,8 @@ func Create(dir string) *GoTime {
 	g := &GoTime{Dir: dir}
 	g.timeFormat = "20060102T150405Z"
 
+	g.CurrDataFile = time.Now().Format("2006-01.data")
+
 	g.files = g.getTimerFiles()
 	for _, f := range g.files {
 		g.addTimersFromFile(f)
@@ -64,6 +70,13 @@ func (g *GoTime) GetAllTimers() []Timer {
 	return g.timers
 }
 
+func (g *GoTime) GetTimer(id int) (*Timer, error) {
+	if len(g.timers) >= id {
+		return &g.timers[len(g.timers)-id], nil
+	}
+	return nil, errors.New("Invalid Timer Id")
+}
+
 // getTimerFiles Returns a string slice of all of the data file names
 func (g *GoTime) getTimerFiles() []string {
 	var ret []string
@@ -79,61 +92,27 @@ func (g *GoTime) getTimerFiles() []string {
 
 // addTimersFromFile Adds all timer lines from g.Dir/data/f and adds a timer for it
 func (g *GoTime) addTimersFromFile(f string) error {
-	content, err := ioutil.ReadFile(g.Dir + "/data/" + f)
+	lines, err := g.readDataFile(f)
 	if err != nil {
-		fmt.Println(err)
 		return err
 	}
-	cntString := strings.TrimSpace(string(content))
 
-	lines := strings.Split(cntString, "\n")
 	for i := range lines {
-		if err = g.AddTimerFromString(lines[i]); err != nil {
+		t, err := CreateTimerFromString(lines[i])
+		if err != nil {
 			return err
 		}
-	}
-	return err
-}
-
-// AddTimerFromString takes a string in the format of the lines from the data file
-// and builds a timer from it.
-func (g *GoTime) AddTimerFromString(st string) error {
-	var err error
-	t := new(Timer)
-	flds := strings.Fields(st)
-	if len(flds) > 1 && flds[0] == "inc" {
-		// Start Time
-		if len(flds) >= 2 {
-			if t.Beg, err = time.Parse(g.timeFormat, flds[1]); err != nil {
-				return err
-			}
-		}
-		// End Time
-		if len(flds) >= 4 && flds[2] == "-" {
-			if t.End, err = time.Parse(g.timeFormat, flds[3]); err != nil {
-				return err
-			}
-		}
-		var inTags bool
-		for i := range flds {
-			if flds[i] == "#" {
-				inTags = true
-				continue
-			}
-			if inTags {
-				tg := strings.Trim(flds[i], "\"")
-				t.Tags = append(t.Tags, tg)
-				g.AddTag(tg)
-			}
-		}
 		if !t.Beg.IsZero() {
 			g.timers = append(g.timers, *t)
+			for i := range t.Tags {
+				g.AddTag(t.Tags[i])
+			}
 		}
 	}
 	return err
 }
 
-// AddTag adds a tag to list of all used tags
+// AddTag adds a tag to the list of all used tags
 func (g *GoTime) AddTag(tg string) {
 	if !g.HasTag(tg) {
 		g.Tags = append(g.Tags, tg)
@@ -158,10 +137,10 @@ func (g *GoTime) StartTimer() *Timer {
 	t := new(Timer)
 	t.Beg = time.Now()
 	g.timers = append(g.timers, *t)
-	// TODO: Add a line to the YYYY-MM.data file
-	// TODO: Update the Undo File
-	g.ResetIds()
 
+	g.AddTimerToCurrentDataFile(t)
+
+	g.ResetIds()
 	return g.Status()
 }
 
@@ -170,16 +149,247 @@ func (g *GoTime) StopTimer() *Timer {
 	if g.IsRunning() {
 		g.Status().Stop()
 	}
-	// TODO: Add a stop time to the last line in the YYYY-MM.data file
-	// TODO: Update the Undo File
-	return g.Status()
-}
-
-// AddTag adds a new tag to the most recent timer
-func (g *GoTime) AddTagToCurrentTimer(tg string) *Timer {
-	g.Status().AddTag(tg)
-	// TODO: Add the tag to the last line in the YYYY-MM.data file
-	// TODO: Update the Undo File
+	g.UpdateTimerInDataFile(1, g.Status())
 
 	return g.Status()
 }
+
+func (g *GoTime) RemoveTagsFromTimer(id int, tg []string) (*Timer, error) {
+	tmr, err := g.GetTimer(id)
+	if err != nil {
+		return nil, err
+	}
+	for i := range tg {
+		tmr.RemoveTag(tg[i])
+	}
+	err = g.UpdateTimerInDataFile(id, tmr)
+	if err != nil {
+		return nil, err
+	}
+
+	return tmr, nil
+}
+
+func (g *GoTime) AddTagsToTimer(id int, tg []string) (*Timer, error) {
+	tmr, err := g.GetTimer(id)
+	if err != nil {
+		return nil, err
+	}
+	for i := range tg {
+		tmr.AddTag(tg[i])
+	}
+	err = g.UpdateTimerInDataFile(id, tmr)
+	if err != nil {
+		return nil, err
+	}
+
+	return tmr, nil
+}
+
+// AddTag adds new tags to the most recent timer
+func (g *GoTime) AddTagsToCurrentTimer(tgs []string) (*Timer, error) {
+	return g.AddTagsToTimer(1, tgs)
+}
+
+func (g *GoTime) AddTimerToCurrentDataFile(tmr *Timer) error {
+	f, err := os.OpenFile(g.Dir+"/data/"+g.CurrDataFile, os.O_APPEND|os.O_WRONLY|os.O_CREATE, 0644)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	_, err = f.WriteString(tmr.ToString())
+	return err
+}
+
+func (g *GoTime) UpdateTimerInDataFile(id int, tmr *Timer) error {
+	var err error
+	var datFileNm string
+	var txn *Transaction
+
+	// We have to step back through the files to find this id
+	var lines []string
+	var linesCnt int
+
+	for i := len(g.files) - 1; i >= 0; i-- {
+		lines, err = g.readDataFile(g.files[i])
+		if err != nil {
+			return err
+		} else {
+			if linesCnt+len(lines) >= id {
+				datFileNm = g.files[i]
+			}
+		}
+		if datFileNm != "" {
+			break
+		}
+		linesCnt += len(lines)
+	}
+
+	// datFileNm should be the right data file, linesCnt should be the starting index in that file
+	// We have to find the line in the file that is (id-linesCnt) lines from the bottom
+	// First back the file up, in case something messes up
+	if err = g.backupDataFile(datFileNm); err != nil {
+		return err
+	}
+
+	var f *os.File
+	f, err = os.OpenFile(g.Dir+"/data/"+datFileNm, os.O_RDWR|os.O_TRUNC, 0666)
+
+	for i := range lines {
+		if linesCnt+(len(lines)-i) == id {
+			// Found the timer line
+			if _, err = f.WriteString(tmr.ToString() + "\n"); err != nil {
+				break
+			}
+			var oldTmr *Timer
+			oldTmr, err = CreateTimerFromString(lines[i])
+			txn = CreateTxn(oldTmr, tmr)
+		} else {
+			if _, err = f.WriteString(lines[i] + "\n"); err != nil {
+				break
+			}
+		}
+	}
+
+	f.Close()
+
+	if err != nil {
+		// An error occurred, restore the backup
+		if restErr := g.restoreBackupFile(datFileNm); restErr != nil {
+			return errors.New(err.Error() + " (Backup Restore Error: " + restErr.Error() + ")")
+		}
+		return err
+	}
+	// No error, add the transaction to the undo file
+	if undoErr := g.writeTxnToUndoFile(txn); undoErr != nil {
+		return undoErr
+	}
+
+	return err
+}
+
+func (g *GoTime) readDataFile(fn string) ([]string, error) {
+	var lines []string
+	content, err := ioutil.ReadFile(g.Dir + "/data/" + fn)
+	if err != nil {
+		fmt.Println(err)
+		return lines, err
+	}
+	cntString := strings.TrimSpace(string(content))
+
+	lines = strings.Split(cntString, "\n")
+	return lines, err
+}
+
+func (g *GoTime) backupDataFile(fn string) error {
+	var err error
+	if _, err = os.Stat(g.Dir + "/data-backups"); err != nil {
+		if err = os.Mkdir(g.Dir+"/data-backups", 0755); err != nil {
+			return err
+		}
+	}
+	return g.copyFile(g.Dir+"/data/"+fn, g.Dir+"/data-backups/"+fn)
+}
+
+func (g *GoTime) restoreBackupFile(fn string) error {
+	var err error
+	if _, err = os.Stat(g.Dir + "/data-backups"); err != nil {
+		if err = os.Mkdir(g.Dir+"/data-backups", 0755); err != nil {
+			return err
+		}
+	}
+	return g.copyFile(g.Dir+"/data-backups/"+fn, g.Dir+"/data/"+fn)
+}
+
+func (g *GoTime) writeTxnToUndoFile(txn *Transaction) error {
+	// TODO: For now we're ignoring the undo file. TimeWarrior doesn't support it yet
+	/*
+		// Backup the undo file
+		var err error
+		var f *os.File
+		err = g.backupDataFile("undo.data")
+		if err != nil {
+			// Couldn't backup undo file...
+			return err
+		}
+		f, err = os.OpenFile(g.Dir+"/data/undo.data", os.O_APPEND|os.O_WRONLY|os.O_CREATE, 0644)
+		if err != nil {
+			return err
+		}
+
+		f.Close()
+
+		if _, err = f.WriteString(txn.ToString()); err != nil {
+			undoErr := g.restoreBackupFile("undo.data")
+			if undoErr != nil {
+				return errors.New(err.Error() + " (Backup Restore Error: " + undoErr.Error() + ")")
+			}
+			return err
+		}
+	*/
+	return nil
+}
+
+func (g *GoTime) copyFile(src, dst string) (err error) {
+	sfi, err := os.Stat(src)
+	if err != nil {
+		return
+	}
+	if !sfi.Mode().IsRegular() {
+		// cannot copy non-regular files (e.g., directories,
+		// symlinks, devices, etc.)
+		return fmt.Errorf("CopyFile: non-regular source file %s (%q)", sfi.Name(), sfi.Mode().String())
+	}
+	dfi, err := os.Stat(dst)
+	if err != nil {
+		if !os.IsNotExist(err) {
+			return
+		}
+	} else {
+		if !(dfi.Mode().IsRegular()) {
+			return fmt.Errorf("CopyFile: non-regular destination file %s (%q)", dfi.Name(), dfi.Mode().String())
+		}
+		if os.SameFile(sfi, dfi) {
+			return
+		}
+	}
+	if err = os.Link(src, dst); err == nil {
+		return
+	}
+	err = g.copyFileContents(src, dst)
+	return
+}
+
+func (g *GoTime) copyFileContents(src, dst string) (err error) {
+	in, err := os.Open(src)
+	if err != nil {
+		return
+	}
+	defer in.Close()
+	out, err := os.Create(dst)
+	if err != nil {
+		return
+	}
+	defer func() {
+		cerr := out.Close()
+		if err == nil {
+			err = cerr
+		}
+	}()
+	if _, err = io.Copy(out, in); err != nil {
+		return
+	}
+	err = out.Sync()
+	return
+}
+
+func TagIsMultiword(tg string) bool {
+	if strings.Contains(tg, " ") {
+		return true
+	}
+	if strings.Contains(tg, "-") {
+		return true
+	}
+	return false
+}
diff --git a/timer.go b/timer.go
index cf35bfc..35cf067 100644
--- a/timer.go
+++ b/timer.go
@@ -7,10 +7,46 @@ import (
 )
 
 type Timer struct {
-	Id   int
-	Beg  time.Time
-	End  time.Time
-	Tags []string
+	Id         int
+	Beg        time.Time
+	End        time.Time
+	Tags       []string
+	timeFormat string
+}
+
+// CreateTimerFromString takes a string in the format of the lines from the data file
+// and builds a timer from it.
+func CreateTimerFromString(st string) (*Timer, error) {
+	var err error
+	t := new(Timer)
+	t.timeFormat = "20060102T150405Z"
+	flds := strings.Fields(st)
+	if len(flds) > 1 && flds[0] == "inc" {
+		// Start Time
+		if len(flds) >= 2 {
+			if t.Beg, err = time.Parse(t.timeFormat, flds[1]); err != nil {
+				return t, err
+			}
+		}
+		// End Time
+		if len(flds) >= 4 && flds[2] == "-" {
+			if t.End, err = time.Parse(t.timeFormat, flds[3]); err != nil {
+				return t, err
+			}
+		}
+		var inTags bool
+		for i := range flds {
+			if flds[i] == "#" {
+				inTags = true
+				continue
+			}
+			if inTags {
+				tg := strings.Trim(flds[i], "\"")
+				t.AddTag(tg)
+			}
+		}
+	}
+	return t, err
 }
 
 func (t *Timer) Start() {
@@ -88,8 +124,12 @@ func (t *Timer) ToString() string {
 	if len(t.Tags) > 0 {
 		ret += " # "
 		for i := range t.Tags {
-			if strings.Contains(t.Tags[i], " ") {
-				ret += "\"" + t.Tags[i] + "\""
+			if TagIsMultiword(t.Tags[i]) {
+				ret += "\""
+			}
+			ret += t.Tags[i]
+			if TagIsMultiword(t.Tags[i]) {
+				ret += "\""
 			}
 			ret += " "
 		}
diff --git a/transaction.go b/transaction.go
index c754ac5..89df269 100644
--- a/transaction.go
+++ b/transaction.go
@@ -1,7 +1,5 @@
 package gotime
 
-import "time"
-
 type Transaction struct {
 	tp     string
 	before *Timer
@@ -16,8 +14,9 @@ func CreateStartTimerTxns(tmr *Timer) []Transaction {
 
 func CreateStopTimerTxns(tmr *Timer) []Transaction {
 	t1 := CreateIntervalTxn()
-	t1.before = tmr
-	t1.before.End = *new(time.Time)
+	t1.before = new(Timer)
+	t1.before.Beg = tmr.Beg
+	t1.before.Tags = tmr.Tags
 
 	t2 := CreateIntervalTxn()
 	t2.after = tmr
@@ -25,6 +24,26 @@ func CreateStopTimerTxns(tmr *Timer) []Transaction {
 	return []Transaction{*t1, *t2}
 }
 
+func CreateTagChangeTxns(tmr *Timer, oldTags []string) []Transaction {
+	t := CreateIntervalTxn()
+	t.before = new(Timer)
+	t.before.Beg = tmr.Beg
+	t.before.End = tmr.End
+	t.before.Tags = oldTags
+	t.after = tmr
+
+	return []Transaction{*t}
+}
+
+func CreateTxn(oldTmr, newTmr *Timer) *Transaction {
+	t := Transaction{
+		tp:     "interval",
+		before: oldTmr,
+		after:  newTmr,
+	}
+	return &t
+}
+
 func CreateIntervalTxn() *Transaction {
 	t := new(Transaction)
 	t.tp = "interval"
@@ -70,4 +89,12 @@ txn:
   before:
   after: {"start":"20170111T201826Z","end":"20170111T221747Z","tags":["bcw","bcw-gotime","work"]}
 
+	*
+	*
+	* TAG Transaction
+
+txn:
+  type: interval
+  before: {"start":"20170112T123633Z","tags":["bcw","bcw-gotime","work"]}
+  after: {"start":"20170112T123633Z","tags":["bcw","bcw-gotime","test","work"]}
 */