diff --git a/flag.go b/flag.go
new file mode 100644
index 0000000..d1ba757
--- /dev/null
+++ b/flag.go
@@ -0,0 +1,122 @@
+package xls
+
+// Original file header of ParseXL (used as the base for this class):
+// --------------------------------------------------------------------------------
+// Adapted from Excel_Spreadsheet_Reader developed by users bizon153,
+// trex005, and mmp11 (SourceForge.net)
+// https://sourceforge.net/projects/phpexcelreader/
+// Primary changes made by canyoncasa (dvc) for ParseXL 1.00 ...
+//     Modelled moreso after Perl Excel Parse/Write modules
+//     Added Parse_Excel_Spreadsheet object
+//         Reads a whole worksheet or tab as row,column array or as
+//         associated hash of indexed rows and named column fields
+//     Added variables for worksheet (tab) indexes and names
+//     Added an object call for loading individual woorksheets
+//     Changed default indexing defaults to 0 based arrays
+//     Fixed date/time and percent formats
+//     Includes patches found at SourceForge...
+//         unicode patch by nobody
+//         unpack("d") machine depedency patch by matchy
+//         boundsheet utf16 patch by bjaenichen
+//     Renamed functions for shorter names
+//     General code cleanup and rigor, including <80 column width
+//     Included a testcase Excel file and PHP example calls
+//     Code works for PHP 5.x
+
+// Primary changes made by canyoncasa (dvc) for ParseXL 1.10 ...
+// http://sourceforge.net/tracker/index.php?func=detail&aid=1466964&group_id=99160&atid=623334
+//     Decoding of formula conditions, results, and tokens.
+//     Support for user-defined named cells added as an array "namedcells"
+//         Patch code for user-defined named cells supports single cells only.
+//         NOTE: this patch only works for BIFF8 as BIFF5-7 use a different
+//         external sheet reference structure
+
+// ParseXL definitions
+const XLS_BIFF8 = 0x0600
+const XLS_BIFF7 = 0x0500
+const XLS_WorkbookGlobals = 0x0005
+const XLS_Worksheet = 0x0010
+
+// record identifiers
+const XLS_Type_FORMULA = 0x0006
+const XLS_Type_EOF = 0x000a
+const XLS_Type_PROTECT = 0x0012
+const XLS_Type_OBJECTPROTECT = 0x0063
+const XLS_Type_SCENPROTECT = 0x00dd
+const XLS_Type_PASSWORD = 0x0013
+const XLS_Type_HEADER = 0x0014
+const XLS_Type_FOOTER = 0x0015
+const XLS_Type_EXTERNSHEET = 0x0017
+const XLS_Type_DEFINEDNAME = 0x0018
+const XLS_Type_VERTICALPAGEBREAKS = 0x001a
+const XLS_Type_HORIZONTALPAGEBREAKS = 0x001b
+const XLS_Type_NOTE = 0x001c
+const XLS_Type_SELECTION = 0x001d
+const XLS_Type_DATEMODE = 0x0022
+const XLS_Type_EXTERNNAME = 0x0023
+const XLS_Type_LEFTMARGIN = 0x0026
+const XLS_Type_RIGHTMARGIN = 0x0027
+const XLS_Type_TOPMARGIN = 0x0028
+const XLS_Type_BOTTOMMARGIN = 0x0029
+const XLS_Type_PRINTGRIDLINES = 0x002b
+const XLS_Type_FILEPASS = 0x002f
+const XLS_Type_FONT = 0x0031
+const XLS_Type_CONTINUE = 0x003c
+const XLS_Type_PANE = 0x0041
+const XLS_Type_CODEPAGE = 0x0042
+const XLS_Type_DEFCOLWIDTH = 0x0055
+const XLS_Type_OBJ = 0x005d
+const XLS_Type_COLINFO = 0x007d
+const XLS_Type_IMDATA = 0x007f
+const XLS_Type_SHEETPR = 0x0081
+const XLS_Type_HCENTER = 0x0083
+const XLS_Type_VCENTER = 0x0084
+const XLS_Type_SHEET = 0x0085
+const XLS_Type_PALETTE = 0x0092
+const XLS_Type_SCL = 0x00a0
+const XLS_Type_PAGESETUP = 0x00a1
+const XLS_Type_MULRK = 0x00bd
+const XLS_Type_MULBLANK = 0x00be
+const XLS_Type_DBCELL = 0x00d7
+const XLS_Type_XF = 0x00e0
+const XLS_Type_MERGEDCELLS = 0x00e5
+const XLS_Type_MSODRAWINGGROUP = 0x00eb
+const XLS_Type_MSODRAWING = 0x00ec
+const XLS_Type_SST = 0x00fc
+const XLS_Type_LABELSST = 0x00fd
+const XLS_Type_EXTSST = 0x00ff
+const XLS_Type_EXTERNALBOOK = 0x01ae
+const XLS_Type_DATAVALIDATIONS = 0x01b2
+const XLS_Type_TXO = 0x01b6
+const XLS_Type_HYPERLINK = 0x01b8
+const XLS_Type_DATAVALIDATION = 0x01be
+const XLS_Type_DIMENSION = 0x0200
+const XLS_Type_BLANK = 0x0201
+const XLS_Type_NUMBER = 0x0203
+const XLS_Type_LABEL = 0x0204
+const XLS_Type_BOOLERR = 0x0205
+const XLS_Type_STRING = 0x0207
+const XLS_Type_ROW = 0x0208
+const XLS_Type_INDEX = 0x020b
+const XLS_Type_ARRAY = 0x0221
+const XLS_Type_DEFAULTROWHEIGHT = 0x0225
+const XLS_Type_WINDOW2 = 0x023e
+const XLS_Type_RK = 0x027e
+const XLS_Type_STYLE = 0x0293
+const XLS_Type_FORMAT = 0x041e
+const XLS_Type_SHAREDFMLA = 0x04bc
+const XLS_Type_BOF = 0x0809
+const XLS_Type_SHEETPROTECTION = 0x0867
+const XLS_Type_RANGEPROTECTION = 0x0868
+const XLS_Type_SHEETLAYOUT = 0x0862
+const XLS_Type_XFEXT = 0x087d
+const XLS_Type_PAGELAYOUTVIEW = 0x088b
+const XLS_Type_UNKNOWN = 0xffff
+
+// Encryption type
+const MS_BIFF_CRYPTO_NONE = 0
+const MS_BIFF_CRYPTO_XOR = 1
+const MS_BIFF_CRYPTO_RC4 = 2
+
+// Size of stream blocks when using RC4 encryption
+const REKEY_BLOCK = 0x400
diff --git a/workbook.go b/workbook.go
index 58d697b..47b2438 100644
--- a/workbook.go
+++ b/workbook.go
@@ -8,7 +8,7 @@ import (
 	"unicode/utf16"
 )
 
-//xls workbook type
+//WorkBook excel work book
 type WorkBook struct {
 	Debug          bool
 	Is5ver         bool
@@ -28,7 +28,7 @@ type WorkBook struct {
 	dateMode       uint16
 }
 
-//read workbook from ole2 file
+//newWorkBookFromOle2 read workbook from ole2 file
 func newWorkBookFromOle2(rs io.ReadSeeker) *WorkBook {
 	var wb = &WorkBook{
 		rs:      rs,
@@ -69,17 +69,17 @@ func (wb *WorkBook) parseBof(buf io.ReadSeeker, b *bof, pre *bof, offset_pre int
 	binary.Read(buf, binary.LittleEndian, bts)
 	item := bytes.NewReader(bts)
 	switch b.Id {
-	case 0x0809: // BOF
+	case XLS_Type_BOF:
 		bif := new(biffHeader)
 		binary.Read(item, binary.LittleEndian, bif)
 		if bif.Ver != 0x600 {
 			wb.Is5ver = true
 		}
 		wb.Type = bif.Type
-	case 0x0042: // CODEPAGE
+	case XLS_Type_CODEPAGE:
 		binary.Read(item, binary.LittleEndian, &wb.Codepage)
-	case 0x003c: // SST CONTINUE identifier
-		if pre.Id == 0x00fc {
+	case XLS_Type_CONTINUE:
+		if pre.Id == XLS_Type_SST {
 			var err error
 			var str string
 			var size uint16
@@ -106,7 +106,7 @@ func (wb *WorkBook) parseBof(buf io.ReadSeeker, b *bof, pre *bof, offset_pre int
 		offset = offset_pre
 		after = pre
 		after_using = b
-	case 0x00fc: // SST identifier
+	case XLS_Type_SST:
 		info := new(SstInfo)
 		binary.Read(item, binary.LittleEndian, info)
 		wb.sst = make([]string, info.Count)
@@ -125,18 +125,18 @@ func (wb *WorkBook) parseBof(buf io.ReadSeeker, b *bof, pre *bof, offset_pre int
 			}
 		}
 		offset = i
-	case 0x0085: // SHEET
+	case XLS_Type_SHEET:
 		var bs = new(boundsheet)
 		binary.Read(item, binary.LittleEndian, bs)
 		// different for BIFF5 and BIFF8
 		wb.addSheet(bs, item)
-	case 0x0017: // EXTERNSHEET
+	case XLS_Type_EXTERNSHEET:
 		if !wb.Is5ver {
 			binary.Read(item, binary.LittleEndian, &wb.ref.Num)
 			wb.ref.Info = make([]ExtSheetInfo, wb.ref.Num)
 			binary.Read(item, binary.LittleEndian, &wb.ref.Info)
 		}
-	case 0x00e0: // XF
+	case XLS_Type_XF:
 		if wb.Is5ver {
 			xf := new(Xf5)
 			binary.Read(item, binary.LittleEndian, xf)
@@ -146,11 +146,11 @@ func (wb *WorkBook) parseBof(buf io.ReadSeeker, b *bof, pre *bof, offset_pre int
 			binary.Read(item, binary.LittleEndian, xf)
 			wb.addXf(xf)
 		}
-	case 0x0031: // FONT
+	case XLS_Type_FONT:
 		f := new(FontInfo)
 		binary.Read(item, binary.LittleEndian, f)
 		wb.addFont(f, item)
-	case 0x041e: //FORMAT
+	case XLS_Type_FORMAT:
 		format := new(Format)
 		binary.Read(item, binary.LittleEndian, &format.Head)
 		if raw, err := wb.parseString(item, format.Head.Size, "format"); nil == err && "" != raw {
@@ -160,7 +160,7 @@ func (wb *WorkBook) parseBof(buf io.ReadSeeker, b *bof, pre *bof, offset_pre int
 		}
 
 		wb.addFormat(format)
-	case 0x0022: //DATEMODE
+	case XLS_Type_DATEMODE:
 		binary.Read(item, binary.LittleEndian, &wb.dateMode)
 	}
 	return
@@ -311,7 +311,7 @@ func (w *WorkBook) GetSheet(num int) *WorkSheet {
 	return nil
 }
 
-//Get the number of all sheets, look into example
+//NumSheets Get the number of all sheets, look into example
 func (w *WorkBook) NumSheets() int {
 	return len(w.sheets)
 }