diff --git a/assets/webui/ofdgo.js b/assets/webui/ofdgo.js
index 75ae385..325ef31 100644
--- a/assets/webui/ofdgo.js
+++ b/assets/webui/ofdgo.js
@@ -1,4 +1,4 @@
-import { CanvasEditor, canEditObject, editTextValue, richTextModel, fontFaceStyle, missingGlyphMessage, objectEditReason, selectedText, lineShape, selectionBounds, pagePoint } from "./ofdgo_edit.js";
+import { SVG_NAMESPACE, CanvasEditor, canEditObject, editTextValue, richTextModel, fontFaceStyle, missingGlyphMessage, objectEditReason, selectedText, lineShape, selectionBounds, pagePoint } from "./ofdgo_edit.js";
 import { FontManager, FontPicker } from "./ofdgo_font.js";
 
 const MM_TO_PX = 96 / 25.4;
@@ -9063,9 +9063,9 @@ function mountPageLinks(page, surface) {
 		anchor.style.height = `${link.height / page.height * 100}%`;
 		if (link.path) {
 			anchor.classList.add("page-region-link");
-			const region = document.createElementNS("http://www.w3.org/2000/svg", "svg");
+			const region = document.createElementNS(SVG_NAMESPACE, "svg");
 			region.setAttribute("viewBox", `${link.x} ${link.y} ${link.width} ${link.height}`);
-			const path = document.createElementNS("http://www.w3.org/2000/svg", "path");
+			const path = document.createElementNS(SVG_NAMESPACE, "path");
 			path.setAttribute("d", link.path);
 			region.append(path);
 			anchor.append(region);
diff --git a/assets/webui/ofdgo_edit.js b/assets/webui/ofdgo_edit.js
index 15393e9..5bc4e62 100644
--- a/assets/webui/ofdgo_edit.js
+++ b/assets/webui/ofdgo_edit.js
@@ -1,4 +1,5 @@
 const PX_PER_MM = 96 / 25.4;
+export const SVG_NAMESPACE = "http://www.w3.org/2000/svg";
 
 const FORMAT_KEYS = ["font", "size", "color", "bold", "italic", "underline", "strikeout", "shadow", "background"];
 const RICH_CLIPBOARD = "application/x-ofdgo-rich-text";
@@ -620,18 +621,18 @@ export class CanvasEditor {
 			}
 			if (object.type === "PathObject" && (object.shape || object.outline || object.contours?.length)) {
 				node.classList.add("edit-contour");
-				const svg = document.createElementNS("http://www.w3.org/2000/svg", "svg");
+				const svg = document.createElementNS(SVG_NAMESPACE, "svg");
 				svg.classList.add("edit-outline");
 				svg.setAttribute("preserveAspectRatio", "none");
 				let contour;
 				if (object.shape || object.oriented || !object.contours?.length) {
 					const shape = object.shape || object.oriented?.kind;
-					contour = document.createElementNS("http://www.w3.org/2000/svg", shape === "line" ? "line" : shape === "ellipse" ? "ellipse" : shape === "rectangle" ? "rect" : "path");
+					contour = document.createElementNS(SVG_NAMESPACE, shape === "line" ? "line" : shape === "ellipse" ? "ellipse" : shape === "rectangle" ? "rect" : "path");
 					if (!shape) contour.setAttribute("d", object.outline);
 					svg.append(contour);
 				} else {
 					for (const path of object.contours) {
-						const contour = document.createElementNS("http://www.w3.org/2000/svg", "path");
+						const contour = document.createElementNS(SVG_NAMESPACE, "path");
 						contour.setAttribute("d", path.path);
 						svg.append(contour);
 					}
@@ -1354,10 +1355,10 @@ export class CanvasEditor {
 	}
 
 	createPreview(surface, page, shape, style) {
-		const preview = document.createElementNS("http://www.w3.org/2000/svg", "svg");
+		const preview = document.createElementNS(SVG_NAMESPACE, "svg");
 		preview.classList.add("edit-preview");
 		preview.setAttribute("viewBox", `0 0 ${page.width} ${page.height}`);
-		const node = document.createElementNS("http://www.w3.org/2000/svg", lineShape(shape) && shape !== "line" ? "path" : shape === "rectangle" ? "rect" : shape);
+		const node = document.createElementNS(SVG_NAMESPACE, lineShape(shape) && shape !== "line" ? "path" : shape === "rectangle" ? "rect" : shape);
 		node.setAttribute("fill", style.fill ? style.fillColor : "none");
 		node.setAttribute("stroke", style.stroke ? style.strokeColor : "none");
 		node.setAttribute("stroke-width", style.lineWidth);
diff --git a/ofdgo_editor_font_binding.go b/ofdgo_editor_font_binding.go
index 4d32cbc..945511d 100644
--- a/ofdgo_editor_font_binding.go
+++ b/ofdgo_editor_font_binding.go
@@ -679,7 +679,7 @@ func checkFontBinding(ctx context.Context, object TextObject, font *FontResource
 	return ctx.Err()
 }
 
-// externalFontName 去除PDF字体子集前缀，不猜测或改写其他名称
+// externalFontName 去除PDF字体子集前缀
 // 入参: name 字体名称
 // 返回: string 外部匹配名称
 func externalFontName(name string) string {
@@ -966,7 +966,7 @@ func pruneUnreferencedFiles(ctx context.Context, reader *Reader, candidates ...s
 				return fmt.Errorf("unknown file dependencies in %s", name)
 			}
 			for _, attr := range node.Attr {
-				if attr.Name.Space != "" && attr.Name.Space != "xmlns" && attr.Name.Space != "http://www.w3.org/XML/1998/namespace" {
+				if attr.Name.Space != "" && attr.Name.Space != "xmlns" && attr.Name.Space != XMLNamespace {
 					uncertain = true
 					return fmt.Errorf("unknown file dependencies in %s", name)
 				}
diff --git a/ofdgo_editor_font_scan.go b/ofdgo_editor_font_scan.go
index 9660148..b4d1177 100644
--- a/ofdgo_editor_font_scan.go
+++ b/ofdgo_editor_font_scan.go
@@ -143,7 +143,7 @@ func scanEditorFontFilesMode(ctx context.Context, reader *Reader, index int, ins
 				return nil
 			}
 			for _, attr := range node.attrs {
-				if attr.Name.Space != "" && attr.Name.Space != "xmlns" && attr.Name.Space != "http://www.w3.org/XML/1998/namespace" {
+				if attr.Name.Space != "" && attr.Name.Space != "xmlns" && attr.Name.Space != XMLNamespace {
 					scan.unsafe = true
 				}
 			}
diff --git a/ofdgo_editor_import.go b/ofdgo_editor_import.go
index 03ad18d..5e38676 100644
--- a/ofdgo_editor_import.go
+++ b/ofdgo_editor_import.go
@@ -671,7 +671,7 @@ func (m *editorPageImport) outlines() ([]byte, error) {
 			if attr.Name.Space == "" || attr.Name.Space == "xmlns" {
 				continue
 			}
-			if attr.Name.Space == "http://www.w3.org/2001/XMLSchema-instance" && (attr.Name.Local == "schemaLocation" || attr.Name.Local == "noNamespaceSchemaLocation") {
+			if attr.Name.Space == XMLSchemaInstanceNamespace && (attr.Name.Local == "schemaLocation" || attr.Name.Local == "noNamespaceSchemaLocation") {
 				continue
 			}
 			return fmt.Errorf("cannot remap outline extension attribute %q", attr.Name.Local)
diff --git a/ofdgo_editor_invoice.go b/ofdgo_editor_invoice.go
index 7e2adbf..aaf9564 100644
--- a/ofdgo_editor_invoice.go
+++ b/ofdgo_editor_invoice.go
@@ -30,7 +30,7 @@ import (
 // invoiceTagType 标识发票票面编辑关联，业务数据保持原规范格式
 const invoiceTagType = "OFDGo.Invoice"
 
-// invoiceNamespace 标识发票编辑关联的命名空间，版本仅随不兼容的语义变更升级
+// invoiceNamespace 表示发票编辑关联命名空间
 const invoiceNamespace = "https://ofdgo.aite.me/ns/invoice/1"
 
 // InvoiceCreateOptions 指定结构化附件名称和可选票面，未指定票面时不新增页面
@@ -1129,7 +1129,7 @@ func invoiceRemapBindings(before, after Invoice, bindings []InvoiceBinding) ([]I
 	return result, nil
 }
 
-// invoiceBindingCoverage 拒绝将未关联的字段修改误报为已同步，不猜测缺失图元
+// invoiceBindingCoverage 检查修改字段的票面关联覆盖情况
 // 入参: before 原发票, after 新发票, bindings 显式关联
 // 返回: error 未绑定字段错误
 func invoiceBindingCoverage(before, after Invoice, bindings []InvoiceBinding) error {
diff --git a/ofdgo_editor_open.go b/ofdgo_editor_open.go
index 9f43e0b..6d026e5 100644
--- a/ofdgo_editor_open.go
+++ b/ofdgo_editor_open.go
@@ -456,7 +456,7 @@ func (e *Editor) repairSourceObjectIDs(data []byte, root *editorXML) ([]byte, bo
 	return editorPatchXML(data, patches), true, nil
 }
 
-// checkDuplicateObjectReferences 拒绝无法判定目标的编号引用，不猜测其所属对象
+// checkDuplicateObjectReferences 检查编号引用的目标歧义
 // 入参: duplicates 重复编号
 // 返回: error 引用歧义或读取错误
 func (e *Editor) checkDuplicateObjectReferences(duplicates map[string]bool) error {
diff --git a/ofdgo_editor_reference.go b/ofdgo_editor_reference.go
index d899d30..fc70402 100644
--- a/ofdgo_editor_reference.go
+++ b/ofdgo_editor_reference.go
@@ -181,7 +181,7 @@ func (s *editorReferenceScan) accept(token xml.Token) bool {
 			}
 		}
 		for _, attr := range token.Attr {
-			if attr.Name.Space == "xmlns" || attr.Name.Local == "xmlns" || attr.Name.Local == "xmlns:ofd" || attr.Name.Space == "http://www.w3.org/XML/1998/namespace" {
+			if attr.Name.Space == "xmlns" || attr.Name.Local == "xmlns" || attr.Name.Local == "xmlns:ofd" || attr.Name.Space == XMLNamespace {
 				continue
 			}
 			if attr.Name.Space != "" {
diff --git a/ofdgo_editor_resources.go b/ofdgo_editor_resources.go
index a3442fd..486ebb2 100644
--- a/ofdgo_editor_resources.go
+++ b/ofdgo_editor_resources.go
@@ -427,7 +427,7 @@ func normalizeResourceReferences(references map[string]bool) {
 	}
 }
 
-// editorResourceNode 按资源标识查找标准资源节点，等价别名冲突时不猜测
+// editorResourceNode 按资源标识查找标准资源节点并检查别名冲突
 // 入参: root 资源文件根节点, group 资源集合名称, kind 资源类型, id 资源标识
 // 返回: *editorXML 资源节点，未找到时为nil
 func editorResourceNode(root *editorXML, group, kind, id string) *editorXML {
diff --git a/ofdgo_invoice.go b/ofdgo_invoice.go
index 2013b33..605239c 100644
--- a/ofdgo_invoice.go
+++ b/ofdgo_invoice.go
@@ -23,7 +23,7 @@ import (
 	"strings"
 )
 
-// 发票读取限额，不扫描未声明资源或嵌套附件包
+// 发票读取限额
 const (
 	invoiceXMLLimit    = 16 << 20
 	invoiceTotalLimit  = 64 << 20
@@ -63,7 +63,7 @@ type Invoice struct {
 	Facts       []InvoiceFact   `json:"facts,omitempty"`
 }
 
-// InvoiceParty 保存购销双方信息，不从名称或其他字段推测税号
+// InvoiceParty 保存购销双方信息
 type InvoiceParty struct {
 	Name    string `json:"name,omitempty"`
 	TaxID   string `json:"taxId,omitempty"`
@@ -94,7 +94,7 @@ type InvoiceSource struct {
 	NodePath string `json:"nodePath,omitempty"`
 }
 
-// InvoiceIssue 保存来源明确的解析诊断，Code为机器可读类别，不包含真伪判断
+// InvoiceIssue 保存来源明确的解析诊断，Code为机器可读类别
 type InvoiceIssue struct {
 	Code    string        `json:"code"`
 	Message string        `json:"message"`
@@ -103,7 +103,7 @@ type InvoiceIssue struct {
 }
 
 // InvoiceFact 保存命名空间限定的业务事实、原始数值及精度属性，Nil与空文本分别表达
-// References保留对象引用标引的原始页标识和有序图元标识，不推测明细归属
+// References保留对象引用标引的原始页标识和有序图元标识
 type InvoiceFact struct {
 	Name       string               `json:"name"`
 	Namespace  string               `json:"namespace,omitempty"`
diff --git a/ofdgo_invoice_layout.go b/ofdgo_invoice_layout.go
index 09f5705..8f5f5fd 100644
--- a/ofdgo_invoice_layout.go
+++ b/ofdgo_invoice_layout.go
@@ -70,7 +70,7 @@ func invoiceAppearanceMatches(text TextObject, value string) bool {
 	return actual == expected
 }
 
-// invoiceLayoutFields 按稳定顺序展开公共字段及明细，不推算缺失值
+// invoiceLayoutFields 按稳定顺序展开公共字段及明细
 // 入参: invoice 发票数据
 // 返回: []invoiceLayoutField 字段列表
 func invoiceLayoutFields(invoice Invoice) []invoiceLayoutField {
@@ -181,11 +181,11 @@ func invoiceLayoutFactVisible(invoice Invoice, fact InvoiceFact) bool {
 // 入参: value 发票，fact 原始字段
 // 返回: 公共字段关联及是否明确映射
 func invoiceEDRMFactBinding(value Invoice, fact InvoiceFact) (InvoiceBinding, bool) {
-	if value.Standard != invoiceEDRM && value.Standard != ofdNamespace2016 || fact.Namespace != value.Standard {
+	if value.Standard != InvoiceStandardEDRM2019 && value.Standard != ofdNamespace2016 || fact.Namespace != value.Standard {
 		return InvoiceBinding{}, false
 	}
 	var path strings.Builder
-	nodePath := strings.ReplaceAll(fact.Source.NodePath, "{"+invoiceEDRM+"}", "{}")
+	nodePath := strings.ReplaceAll(fact.Source.NodePath, "{"+InvoiceStandardEDRM2019+"}", "{}")
 	if value.Standard == ofdNamespace2016 {
 		nodePath = strings.Replace(nodePath, "/root[1]", "/eInvoice[1]", 1)
 		nodePath = strings.ReplaceAll(nodePath, "/", "/{}")
diff --git a/ofdgo_invoice_write.go b/ofdgo_invoice_write.go
index 6cc965b..5b3adae 100644
--- a/ofdgo_invoice_write.go
+++ b/ofdgo_invoice_write.go
@@ -81,7 +81,7 @@ type InvoiceContext struct {
 	EndDate    string `json:"endDate,omitempty"`
 }
 
-// InvoiceUnit 保存单一度量的XBRL单位，不推测币种或数量单位
+// InvoiceUnit 保存单一度量的XBRL单位
 type InvoiceUnit struct {
 	ID        string `json:"id"`
 	Namespace string `json:"namespace"`
@@ -121,7 +121,7 @@ type invoiceXMLPatch struct {
 func InvoiceFields(value Invoice) []InvoiceFieldDescriptor {
 	format, supported := invoiceWriteFormat(value)
 	probe := Invoice{Items: []InvoiceItem{{}}}
-	if value.Standard == invoiceEDRM || value.Standard == ofdNamespace2016 {
+	if value.Standard == InvoiceStandardEDRM2019 || value.Standard == ofdNamespace2016 {
 		for _, path := range invoiceEDRMPaths() {
 			item := &probe.Items[0]
 			if value.Standard == ofdNamespace2016 {
@@ -242,7 +242,7 @@ func InvoiceFields(value Invoice) []InvoiceFieldDescriptor {
 // 返回: 已适配格式列表
 func InvoiceFormats() []InvoiceFormat {
 	result := []InvoiceFormat{{Kind: "einv", Standard: InvoiceStandardEInvoice, Version: "0.3", Read: true, Create: true, Edit: true, Items: true}}
-	result = append(result, InvoiceFormat{Kind: "inv", Standard: invoiceEDRM, Version: "1.0", Read: true, Create: true, Edit: true, Items: true})
+	result = append(result, InvoiceFormat{Kind: "inv", Standard: InvoiceStandardEDRM2019, Version: "1.0", Read: true, Create: true, Edit: true, Items: true})
 	result = append(result, InvoiceFormat{Kind: "inv", Standard: ofdNamespace2016, Version: "1.0", Read: true, Create: true, Edit: true})
 	for _, standard := range []string{InvoiceStandardVAT2023, InvoiceStandardDigital2023, InvoiceStandardAir2023, InvoiceStandardRail2023} {
 		kind, version := invoiceTaxonomy(standard)
@@ -268,7 +268,7 @@ func invoiceWriteContext(ctx context.Context) context.Context {
 	return ctx
 }
 
-// invoiceWriteFormat 查找完整格式标识，不推测缺失版本
+// invoiceWriteFormat 按标准、票种和版本查找格式
 // 入参: value 发票
 // 返回: 格式与匹配状态
 func invoiceWriteFormat(value Invoice) (InvoiceFormat, bool) {
@@ -496,7 +496,7 @@ func EncodeInvoiceWithOptions(ctx context.Context, value Invoice, options Invoic
 		return nil, err
 	}
 	var data []byte
-	if value.Standard == invoiceEDRM {
+	if value.Standard == InvoiceStandardEDRM2019 {
 		if len(options.HeaderXML)+len(options.SellerAuthenticationXML)+len(options.TaxSupervisionXML)+len(options.TaxBureauSignatureXML) != 0 {
 			return nil, fmt.Errorf("EDRM creation does not support EInvoice sections")
 		}
@@ -646,7 +646,7 @@ func invoiceWriteRepresented(want, got Invoice) error {
 	return nil
 }
 
-// invoiceEncodeXBRL 构造单主体实例，扩展事实不得携带无法重建的上下文或元组
+// invoiceEncodeXBRL 构造单主体XBRL实例
 // 入参: value 发票，options 显式分类标准、上下文和单位
 // 返回: XBRL数据及表达错误
 func invoiceEncodeXBRL(value Invoice, options InvoiceEncodingOptions) ([]byte, error) {
@@ -663,7 +663,7 @@ func invoiceEncodeXBRL(value Invoice, options InvoiceEncodingOptions) ([]byte, e
 	}
 	var b strings.Builder
 	b.WriteString(xml.Header)
-	fmt.Fprintf(&b, `<xbrli:xbrl xmlns:xbrli="%s" xmlns:xsi="%s" xmlns:iso4217="%s" xmlns:f="%s" xmlns:link="%s" xmlns:xlink="%s">`, invoiceXBRL, invoiceXSI, InvoiceCurrencyNamespace, value.Standard, invoiceLinkbase, invoiceXLink)
+	fmt.Fprintf(&b, `<xbrli:xbrl xmlns:xbrli="%s" xmlns:xsi="%s" xmlns:iso4217="%s" xmlns:f="%s" xmlns:link="%s" xmlns:xlink="%s">`, invoiceXBRL, XMLSchemaInstanceNamespace, InvoiceCurrencyNamespace, value.Standard, invoiceLinkbase, XLinkNamespace)
 	fmt.Fprintf(&b, `<link:schemaRef xlink:type="simple" xlink:href="%s"/><xbrli:context id="%s"><xbrli:entity><xbrli:identifier scheme="%s">%s</xbrli:identifier></xbrli:entity><xbrli:period>`, invoiceWriteEscape(options.SchemaRef), options.Context.ID, invoiceWriteEscape(options.Context.Scheme), invoiceWriteEscape(options.Context.Identifier))
 	if options.Context.Instant != "" {
 		if options.Context.StartDate != "" || options.Context.EndDate != "" {
@@ -829,7 +829,7 @@ func invoicePlainGroups() []invoiceWriteField {
 	return []invoiceWriteField{{"SellerInformation", "SellerIdNum SellerName SellerAddr SellerTelNum SellerBankName SellerBankAccNum"}, {"BuyerInformation", "BuyerIdNum BuyerName"}, {"BasicInformation", "TotalAmWithoutTax TotalTaxAm TotalTax-includedAmount"}, {"AdditionalInformation", "Remark"}}
 }
 
-// invoiceEncodePlain 构造官方0.3字段路径，不捏造税务签名或编号
+// invoiceEncodePlain 构造0.3版电子发票业务XML
 // 入参: value 发票
 // 返回: XML及不可表达的扩展错误
 func invoiceEncodePlain(value Invoice) ([]byte, error) {
@@ -1002,7 +1002,7 @@ func PatchInvoice(ctx context.Context, data []byte, changes []InvoiceFieldChange
 		if change.Revision != "" && change.Revision != revision {
 			return nil, fmt.Errorf("stale invoice source revision")
 		}
-		oldNil := invoiceXMLAttr(s.node, invoiceXSI, "nil")
+		oldNil := invoiceXMLAttr(s.node, XMLSchemaInstanceNamespace, "nil")
 		isNil := oldNil == "true" || oldNil == "1"
 		expectedNil := false
 		if change.ExpectedNil != nil {
@@ -1082,7 +1082,7 @@ func invoiceValidateXMLWrite(ctx context.Context, before, after []byte) error {
 	return nil
 }
 
-// invoiceWriteXMLProblems 按节点路径及问题值区分诊断，避免不同候选的同类问题相互抵消
+// invoiceWriteXMLProblems 按节点路径及问题值归类诊断
 // 入参: ctx 上下文，data 原文，tuples 是否检查元组必有字段
 // 返回: 定位诊断及解析错误
 func invoiceWriteXMLProblems(ctx context.Context, data []byte, tuples bool) (map[string]InvoiceIssue, error) {
@@ -1112,11 +1112,11 @@ func invoiceWriteXMLProblems(ctx context.Context, data []byte, tuples bool) (map
 		}
 		path += "/" + n.name.Local
 		kind, _ := invoiceTaxonomy(n.name.Space)
-		nilValue := invoiceXMLAttr(n, invoiceXSI, "nil")
+		nilValue := invoiceXMLAttr(n, XMLSchemaInstanceNamespace, "nil")
 		empty := nilValue == "true" || nilValue == "1"
 		date := kind != "" && invoiceWriteDateFact(kind, n.name.Local)
 		plainDate := root.name == (xml.Name{Local: "EInvoice"}) && path == "/EInvoice/TaxSupervisionInfo/IssueTime"
-		edrmDate := n.parent == root && n.name == (xml.Name{Space: invoiceEDRM, Local: "IssueDate"})
+		edrmDate := n.parent == root && n.name == (xml.Name{Space: InvoiceStandardEDRM2019, Local: "IssueDate"})
 		if len(n.children) == 0 && !empty && (date || plainDate || edrmDate) {
 			value := n.text.String()
 			parseValue := value
@@ -1157,7 +1157,7 @@ func invoiceWriteXMLProblems(ctx context.Context, data []byte, tuples bool) (map
 		return nil, err
 	}
 	for _, value := range report.Invoices {
-		if value.Standard != invoiceEDRM {
+		if value.Standard != InvoiceStandardEDRM2019 {
 			continue
 		}
 		issues, err := ValidateInvoice(ctx, value)
@@ -1171,7 +1171,7 @@ func invoiceWriteXMLProblems(ctx context.Context, data []byte, tuples bool) (map
 	for _, issue := range report.Issues {
 		value := ""
 		if n := nodes[issue.Source.NodePath]; n != nil {
-			value = n.text.String() + "\x00" + invoiceXMLAttr(n, invoiceXSI, "nil")
+			value = n.text.String() + "\x00" + invoiceXMLAttr(n, XMLSchemaInstanceNamespace, "nil")
 		}
 		add(issue, value)
 	}
@@ -1196,14 +1196,14 @@ func invoiceWriteLeaf(n *invoiceXMLNode, value string, nilValue bool) ([]byte, e
 		start.Attr = append(start.Attr, xml.Attr{Name: xml.Name{Local: "xmlns:" + prefix}, Value: n.ns[prefix]})
 	}
 	for _, a := range n.attrs {
-		if a.Name.Space == "xmlns" || a.Name.Local == "xmlns" && a.Name.Space == "" || a.Name.Space == invoiceXSI && a.Name.Local == "nil" || nilValue && a.Name.Space == "" && (a.Name.Local == "decimals" || a.Name.Local == "precision") {
+		if a.Name.Space == "xmlns" || a.Name.Local == "xmlns" && a.Name.Space == "" || a.Name.Space == XMLSchemaInstanceNamespace && a.Name.Local == "nil" || nilValue && a.Name.Space == "" && (a.Name.Local == "decimals" || a.Name.Local == "precision") {
 			continue
 		}
 		start.Attr = append(start.Attr, a)
 	}
 	if nilValue {
-		start.Attr = append(start.Attr, xml.Attr{Name: xml.Name{Space: invoiceXSI, Local: "nil"}, Value: "true"})
-	} else if invoiceXMLAttr(n, invoiceXSI, "nil") == "true" || invoiceXMLAttr(n, invoiceXSI, "nil") == "1" {
+		start.Attr = append(start.Attr, xml.Attr{Name: xml.Name{Space: XMLSchemaInstanceNamespace, Local: "nil"}, Value: "true"})
+	} else if invoiceXMLAttr(n, XMLSchemaInstanceNamespace, "nil") == "true" || invoiceXMLAttr(n, XMLSchemaInstanceNamespace, "nil") == "1" {
 		kind, _ := invoiceTaxonomy(n.name.Space)
 		if invoiceNumeric(kind, n.name.Local) {
 			start.Attr = append(start.Attr, xml.Attr{Name: xml.Name{Local: "decimals"}, Value: "INF"})
@@ -1288,7 +1288,7 @@ func UpdateInvoiceXML(ctx context.Context, data []byte, invoiceIndex int, value
 	if err = invoiceWriteNewIssues(filter(oldIssues), filter(newIssues)); err != nil {
 		return nil, err
 	}
-	if value.Standard == invoiceEDRM {
+	if value.Standard == InvoiceStandardEDRM2019 {
 		return invoiceUpdateEDRM(ctx, data, old, value)
 	}
 	root, spans, err := invoiceWriteSpans(ctx, data)
@@ -1539,7 +1539,7 @@ func invoiceEDRMPaths() []string {
 	return strings.Fields("/eInvoice/InvoiceCode /eInvoice/InvoiceNo /eInvoice/IssueDate /eInvoice/Buyer/BuyerName /eInvoice/Buyer/BuyerTaxID /eInvoice/Seller/SellerName /eInvoice/Seller/SellerTaxID /eInvoice/TaxInclusiveTotalAmount /eInvoice/Note /eInvoice/TaxTotalAmount /eInvoice/TaxExclusiveTotalAmount /eInvoice/GoodsInfos/GoodsInfo/Item /eInvoice/GoodsInfos/GoodsInfo/Specification /eInvoice/GoodsInfos/GoodsInfo/MeasurementDimension /eInvoice/GoodsInfos/GoodsInfo/Quantity /eInvoice/GoodsInfos/GoodsInfo/Price /eInvoice/GoodsInfos/GoodsInfo/Amount /eInvoice/GoodsInfos/GoodsInfo/TaxScheme /eInvoice/GoodsInfos/GoodsInfo/TaxAmount")
 }
 
-// invoiceEncodeEDRM 按2019版路径创建业务XML，不伪造认证字段或丢弃扩展事实
+// invoiceEncodeEDRM 创建2019版电子发票业务XML
 // 入参: value 明确提供的发票业务字段
 // 返回: 独立XML及不可表达错误
 func invoiceEncodeEDRM(value Invoice) ([]byte, error) {
@@ -1551,7 +1551,7 @@ func invoiceEncodeEDRM(value Invoice) ([]byte, error) {
 	}
 	var b strings.Builder
 	b.WriteString(xml.Header)
-	fmt.Fprintf(&b, `<eInvoice xmlns="%s" Version="1.0">`, invoiceEDRM)
+	fmt.Fprintf(&b, `<eInvoice xmlns="%s" Version="1.0">`, InvoiceStandardEDRM2019)
 	write := func(name, text string) {
 		if text != "" {
 			fmt.Fprintf(&b, "<%s>%s</%s>", name, invoiceWriteEscape(text), name)
@@ -1609,7 +1609,7 @@ func invoiceUpdateEDRM(ctx context.Context, data []byte, old, value Invoice) ([]
 	}
 	for _, name := range []string{"Buyer", "Seller", "GoodsInfos"} {
 		changed := name == "GoodsInfos" && !reflect.DeepEqual(old.Items, value.Items) || name == "Buyer" && old.Buyer != value.Buyer || name == "Seller" && old.Seller != value.Seller
-		groups := invoiceChildren(root, invoiceEDRM, name)
+		groups := invoiceChildren(root, InvoiceStandardEDRM2019, name)
 		if len(groups) > 1 {
 			return nil, fmt.Errorf("ambiguous invoice group %s", name)
 		}
@@ -1630,14 +1630,14 @@ func invoiceUpdateEDRM(ctx context.Context, data []byte, old, value Invoice) ([]
 	for _, group := range []string{"", "Buyer", "Seller"} {
 		parent := root
 		if group != "" {
-			parents := invoiceChildren(root, invoiceEDRM, group)
+			parents := invoiceChildren(root, InvoiceStandardEDRM2019, group)
 			if len(parents) > 0 {
 				parent = parents[0]
 			} else {
 				parent = nil
 			}
 		}
-		desired := &invoiceXMLNode{name: xml.Name{Space: invoiceEDRM, Local: group}}
+		desired := &invoiceXMLNode{name: xml.Name{Space: InvoiceStandardEDRM2019, Local: group}}
 		var names []string
 		for _, path := range invoiceEDRMPaths() {
 			parts := strings.Split(path, "/")
@@ -1651,10 +1651,10 @@ func invoiceUpdateEDRM(ctx context.Context, data []byte, old, value Invoice) ([]
 			}
 			name := parts[len(parts)-1]
 			names = append(names, name)
-			node := &invoiceXMLNode{name: xml.Name{Space: invoiceEDRM, Local: name}}
+			node := &invoiceXMLNode{name: xml.Name{Space: InvoiceStandardEDRM2019, Local: name}}
 			text := *target
 			if name == "IssueDate" && parent != nil {
-				existing := invoiceChildren(parent, invoiceEDRM, name)
+				existing := invoiceChildren(parent, InvoiceStandardEDRM2019, name)
 				if len(existing) == 1 && strings.Contains(existing[0].text.String(), "年") && text != "" {
 					date, err := time.Parse("2006-01-02", text)
 					if err != nil {
@@ -1676,26 +1676,26 @@ func invoiceUpdateEDRM(ctx context.Context, data []byte, old, value Invoice) ([]
 			if err != nil {
 				return nil, err
 			}
-			patch, err := invoiceWriteOrderedInsert(data, spans, root, invoiceEDRM, group, order, raw)
+			patch, err := invoiceWriteOrderedInsert(data, spans, root, InvoiceStandardEDRM2019, group, order, raw)
 			if err != nil {
 				return nil, err
 			}
 			patches = append(patches, patch)
 		} else {
 			for _, name := range names {
-				if len(invoiceChildren(parent, invoiceEDRM, name)) == 0 && group == "" {
-					raw, err := invoiceWriteNode(invoiceChildren(desired, invoiceEDRM, name)[0])
+				if len(invoiceChildren(parent, InvoiceStandardEDRM2019, name)) == 0 && group == "" {
+					raw, err := invoiceWriteNode(invoiceChildren(desired, InvoiceStandardEDRM2019, name)[0])
 					if err != nil {
 						return nil, err
 					}
-					patch, err := invoiceWriteOrderedInsert(data, spans, parent, invoiceEDRM, name, order, raw)
+					patch, err := invoiceWriteOrderedInsert(data, spans, parent, InvoiceStandardEDRM2019, name, order, raw)
 					if err != nil {
 						return nil, err
 					}
 					patches = append(patches, patch)
 					continue
 				}
-				changes, err := invoiceWriteMergeChildren(data, spans, parent, desired, invoiceEDRM, []string{name})
+				changes, err := invoiceWriteMergeChildren(data, spans, parent, desired, InvoiceStandardEDRM2019, []string{name})
 				if err != nil {
 					return nil, err
 				}
@@ -1704,15 +1704,15 @@ func invoiceUpdateEDRM(ctx context.Context, data []byte, old, value Invoice) ([]
 		}
 	}
 	if !reflect.DeepEqual(old.Items, value.Items) {
-		generated := &invoiceXMLNode{name: xml.Name{Space: invoiceEDRM, Local: "GoodsInfos"}}
+		generated := &invoiceXMLNode{name: xml.Name{Space: InvoiceStandardEDRM2019, Local: "GoodsInfos"}}
 		for _, item := range value.Items {
-			node := &invoiceXMLNode{name: xml.Name{Space: invoiceEDRM, Local: "GoodsInfo"}}
+			node := &invoiceXMLNode{name: xml.Name{Space: InvoiceStandardEDRM2019, Local: "GoodsInfo"}}
 			for _, path := range invoiceEDRMPaths() {
 				if !strings.HasPrefix(path, "/eInvoice/GoodsInfos/GoodsInfo/") {
 					continue
 				}
 				p, _ := invoiceEDRMField(&value, &item, path)
-				leaf := &invoiceXMLNode{name: xml.Name{Space: invoiceEDRM, Local: path[strings.LastIndexByte(path, '/')+1:]}}
+				leaf := &invoiceXMLNode{name: xml.Name{Space: InvoiceStandardEDRM2019, Local: path[strings.LastIndexByte(path, '/')+1:]}}
 				leaf.text.WriteString(*p)
 				leaf.parts = []invoiceXMLPart{{text: *p}}
 				node.children = append(node.children, leaf)
@@ -1721,7 +1721,7 @@ func invoiceUpdateEDRM(ctx context.Context, data []byte, old, value Invoice) ([]
 			generated.children = append(generated.children, node)
 			generated.parts = append(generated.parts, invoiceXMLPart{child: node})
 		}
-		parents := invoiceChildren(root, invoiceEDRM, "GoodsInfos")
+		parents := invoiceChildren(root, InvoiceStandardEDRM2019, "GoodsInfos")
 		if len(parents) == 0 {
 			raw, err := invoiceWriteNode(generated)
 			if err != nil {
@@ -1801,7 +1801,7 @@ func invoiceWriteUnmapped(before, after []InvoiceFact) error {
 	return nil
 }
 
-// invoiceWriteOriginalOptions 读取原上下文及单位，不猜测或改写定义
+// invoiceWriteOriginalOptions 读取原上下文及单位定义
 // 入参: root 原XML，value 原候选
 // 返回: 原定义及不支持的复杂上下文错误
 func invoiceWriteOriginalOptions(root *invoiceXMLNode, value Invoice) (InvoiceEncodingOptions, error) {
@@ -1815,7 +1815,7 @@ func invoiceWriteOriginalOptions(root *invoiceXMLNode, value Invoice) (InvoiceEn
 	}
 	for _, n := range root.children {
 		if n.name == (xml.Name{Space: invoiceLinkbase, Local: "schemaRef"}) && options.SchemaRef == "" {
-			options.SchemaRef = invoiceXMLAttr(n, invoiceXLink, "href")
+			options.SchemaRef = invoiceXMLAttr(n, XLinkNamespace, "href")
 		}
 		if n.name == (xml.Name{Space: invoiceXBRL, Local: "context"}) && invoiceXMLAttr(n, "", "id") == ref {
 			dims, ok := invoiceContext(n)
@@ -1939,15 +1939,15 @@ func invoiceWriteMergeChildren(data []byte, spans map[string]invoiceXMLSpan, old
 			if len(existing[0].children) > 0 {
 				return nil, fmt.Errorf("non-leaf invoice field %s", name)
 			}
-			if len(targets) == 0 && (existing[0].text.String() == "" || invoiceXMLAttr(existing[0], invoiceXSI, "nil") == "true" || invoiceXMLAttr(existing[0], invoiceXSI, "nil") == "1") {
+			if len(targets) == 0 && (existing[0].text.String() == "" || invoiceXMLAttr(existing[0], XMLSchemaInstanceNamespace, "nil") == "true" || invoiceXMLAttr(existing[0], XMLSchemaInstanceNamespace, "nil") == "1") {
 				continue
 			}
-			if len(targets) > 0 && existing[0].text.String() == targets[0].text.String() && invoiceXMLAttr(existing[0], invoiceXSI, "nil") == invoiceXMLAttr(targets[0], invoiceXSI, "nil") {
+			if len(targets) > 0 && existing[0].text.String() == targets[0].text.String() && invoiceXMLAttr(existing[0], XMLSchemaInstanceNamespace, "nil") == invoiceXMLAttr(targets[0], XMLSchemaInstanceNamespace, "nil") {
 				continue
 			}
 			if len(targets) > 0 {
-				oldNil := invoiceXMLAttr(existing[0], invoiceXSI, "nil")
-				newNil := invoiceXMLAttr(targets[0], invoiceXSI, "nil")
+				oldNil := invoiceXMLAttr(existing[0], XMLSchemaInstanceNamespace, "nil")
+				newNil := invoiceXMLAttr(targets[0], XMLSchemaInstanceNamespace, "nil")
 				wasNil := oldNil == "true" || oldNil == "1"
 				isNil := newNil == "true" || newNil == "1"
 				if !s.empty && wasNil == isNil {
@@ -1995,7 +1995,7 @@ func invoiceWriteMergeItems(ctx context.Context, data []byte, spans map[string]i
 	}
 	space, name := value.Standard, invoiceWriteTuple(value.Kind)
 	names := invoiceWriteItemNames(value.Kind)
-	if value.Standard == invoiceEDRM {
+	if value.Standard == InvoiceStandardEDRM2019 {
 		name = "GoodsInfo"
 		names = strings.Fields("Item Specification MeasurementDimension Quantity Price Amount TaxScheme TaxAmount")
 	} else if value.Standard == InvoiceStandardEInvoice {
@@ -2047,7 +2047,7 @@ func invoiceWriteMergeItems(ctx context.Context, data []byte, spans map[string]i
 		if path == "" {
 			for _, f := range item.Fields {
 				mapped := invoiceItemField(&InvoiceItem{}, value.Kind, f.Name)
-				if value.Standard == InvoiceStandardEInvoice || value.Standard == invoiceEDRM || !invoiceWriteContains(names, f.Name) {
+				if value.Standard == InvoiceStandardEInvoice || value.Standard == InvoiceStandardEDRM2019 || !invoiceWriteContains(names, f.Name) {
 					return nil, fmt.Errorf("unsupported new invoice item fact %s", f.Name)
 				}
 				if mapped != nil {
@@ -2073,12 +2073,12 @@ func invoiceWriteMergeItems(ctx context.Context, data []byte, spans map[string]i
 				continue
 			}
 			s, ok := spans[f.Source.NodePath]
-			if !ok || s.node.parent == nil || s.node.parent.path != path || f.Value != s.node.text.String() || f.Nil != (invoiceXMLAttr(s.node, invoiceXSI, "nil") == "true" || invoiceXMLAttr(s.node, invoiceXSI, "nil") == "1") {
+			if !ok || s.node.parent == nil || s.node.parent.path != path || f.Value != s.node.text.String() || f.Nil != (invoiceXMLAttr(s.node, XMLSchemaInstanceNamespace, "nil") == "true" || invoiceXMLAttr(s.node, XMLSchemaInstanceNamespace, "nil") == "1") {
 				return nil, fmt.Errorf("unmapped item fact changes require PatchInvoice")
 			}
 		}
 		n := original[path]
-		if value.Standard == invoiceEDRM {
+		if value.Standard == InvoiceStandardEDRM2019 {
 			previous := originalItems[path]
 			if err := invoiceWriteUnmapped(previous.Fields, item.Fields); err != nil {
 				return nil, err
@@ -2089,7 +2089,7 @@ func invoiceWriteMergeItems(ctx context.Context, data []byte, spans map[string]i
 				before, _ := invoiceEDRMField(&old, &previous, field)
 				after, _ := invoiceEDRMField(&value, &item, field)
 				if before != nil && after != nil && *before == *after {
-					children := invoiceChildren(n, invoiceEDRM, child.name.Local)
+					children := invoiceChildren(n, InvoiceStandardEDRM2019, child.name.Local)
 					if len(children) == 0 {
 						continue
 					}
@@ -2172,11 +2172,11 @@ func invoiceWriteOrderedInsert(data []byte, spans map[string]invoiceXMLSpan, par
 	return invoiceWriteInsert(spans[parent.path], raw, data)
 }
 
-// invoiceWriteCreation 检查官方元组序列中的必有字段，不虚构缺失业务值
+// invoiceWriteCreation 检查官方元组序列中的必有字段
 // 入参: value 发票
 // 返回: 缺少元组字段错误
 func invoiceWriteCreation(value Invoice) error {
-	if value.Standard == InvoiceStandardEInvoice || value.Standard == invoiceEDRM {
+	if value.Standard == InvoiceStandardEInvoice || value.Standard == InvoiceStandardEDRM2019 {
 		return nil
 	}
 	for i, item := range value.Items {
diff --git a/ofdgo_invoice_xml.go b/ofdgo_invoice_xml.go
index 974ebd3..2c9c49b 100644
--- a/ofdgo_invoice_xml.go
+++ b/ofdgo_invoice_xml.go
@@ -28,30 +28,6 @@ import (
 	"time"
 )
 
-// invoiceXMLNamespace 表示XML预定义命名空间
-const invoiceXMLNamespace = "http://www.w3.org/XML/1998/namespace"
-
-// invoiceXSI 表示XMLSchema实例命名空间
-const invoiceXSI = "http://www.w3.org/2001/XMLSchema-instance"
-
-// invoiceXLink 表示XML链接命名空间
-const invoiceXLink = "http://www.w3.org/1999/xlink"
-
-// invoiceXMLSignature 表示XML数字签名命名空间
-const invoiceXMLSignature = "http://www.w3.org/2000/09/xmldsig#"
-
-// invoiceXBRL 表示XBRL实例命名空间
-const invoiceXBRL = "http://www.xbrl.org/2003/instance"
-
-// invoiceLinkbase 表示XBRL链接库命名空间
-const invoiceLinkbase = "http://www.xbrl.org/2003/linkbase"
-
-// invoiceDimension 表示XBRL实例维度命名空间
-const invoiceDimension = "http://xbrl.org/2006/xbrldi"
-
-// InvoiceCurrencyNamespace 表示InvoiceUnit中ISO货币度量使用的命名空间
-const InvoiceCurrencyNamespace = "http://www.xbrl.org/2003/iso4217"
-
 // InvoiceStandardVAT2023 表示2023版增值税发票分类标准
 const InvoiceStandardVAT2023 = "http://xbrl.mof.gov.cn/taxonomy/2023-12-31/inv"
 
@@ -70,17 +46,29 @@ const InvoiceStandardVAT2021 = "http://xbrl.mof.gov.cn/taxonomy/2021-09-30/inv"
 // InvoiceStandardAir2021 表示2021版航空运输电子客票行程单分类标准
 const InvoiceStandardAir2021 = "http://xbrl.mof.gov.cn/taxonomy/2021-11-30/atr"
 
-// InvoiceStandardEInvoice 表示无命名空间的EInvoice业务标准，版本由Invoice.Version指定
-const InvoiceStandardEInvoice = "EInvoice"
-
-// InvoiceStandardObjectReference 表示基于OFD对象引用的发票标引，业务值来自当前文档的图元
-const InvoiceStandardObjectReference = ofdNamespace2016
-
 // InvoiceStandardEDRM2019 表示2019版电子发票业务标准
 const InvoiceStandardEDRM2019 = "http://www.edrm.org.cn/schema/e-invoice/2019"
 
-// invoiceEDRM 表示2019版电子发票业务命名空间
-const invoiceEDRM = InvoiceStandardEDRM2019
+// InvoiceStandardEInvoice 表示无命名空间的EInvoice业务标准，版本由Invoice.Version指定
+const InvoiceStandardEInvoice = "EInvoice"
+
+// InvoiceStandardObjectReference 表示基于OFD对象引用的发票标引
+const InvoiceStandardObjectReference = ofdNamespace2016
+
+// InvoiceCurrencyNamespace 表示InvoiceUnit中ISO货币度量使用的命名空间
+const InvoiceCurrencyNamespace = "http://www.xbrl.org/2003/iso4217"
+
+// invoiceXBRL 表示XBRL实例命名空间
+const invoiceXBRL = "http://www.xbrl.org/2003/instance"
+
+// invoiceLinkbase 表示XBRL链接库命名空间
+const invoiceLinkbase = "http://www.xbrl.org/2003/linkbase"
+
+// invoiceDimension 表示XBRL实例维度命名空间
+const invoiceDimension = "http://xbrl.org/2006/xbrldi"
+
+// invoiceXMLSignature 表示XML数字签名命名空间
+const invoiceXMLSignature = "http://www.w3.org/2000/09/xmldsig#"
 
 // invoiceDecimalPattern 仅接受XML十进制词法
 var invoiceDecimalPattern = regexp.MustCompile(`^[+-]?(?:[0-9]+(?:\.[0-9]*)?|\.[0-9]+)$`)
@@ -195,7 +183,7 @@ func invoiceXMLTree(ctx context.Context, data []byte) (*invoiceXMLNode, error) {
 					return nil, fmt.Errorf("invoice XML exceeds namespace URI limit")
 				}
 			}
-			n := &invoiceXMLNode{name: v.Name, attrs: v.Attr, parent: current, ns: map[string]string{"xml": invoiceXMLNamespace}, counts: map[xml.Name]int{}, start: d.InputOffset()}
+			n := &invoiceXMLNode{name: v.Name, attrs: v.Attr, parent: current, ns: map[string]string{"xml": XMLNamespace}, counts: map[xml.Name]int{}, start: d.InputOffset()}
 			index := 1
 			if current != nil {
 				for k, v := range current.ns {
@@ -302,7 +290,7 @@ func parseInvoiceXML(ctx context.Context, data []byte, source InvoiceSource) (In
 	if source.Kind == "tag" && invoiceObjectReferences(root) {
 		return report, nil
 	}
-	if root.name == (xml.Name{Local: "EInvoice"}) || root.name.Local == "eInvoice" && (root.name.Space == "" || root.name.Space == invoiceEDRM) {
+	if root.name == (xml.Name{Local: "EInvoice"}) || root.name.Local == "eInvoice" && (root.name.Space == "" || root.name.Space == InvoiceStandardEDRM2019) {
 		return invoicePlainXML(ctx, root, source)
 	}
 	if root.name != (xml.Name{Space: invoiceXBRL, Local: "xbrl"}) {
@@ -413,7 +401,7 @@ func parseInvoiceXML(ctx context.Context, data []byte, source InvoiceSource) (In
 		ref := invoiceXMLAttr(n, "", "contextRef")
 		s := source
 		s.NodePath += n.path
-		fact := InvoiceFact{Name: n.name.Local, Namespace: n.name.Space, Value: n.text.String(), Context: ref, Unit: invoiceXMLAttr(n, "", "unitRef"), Decimals: invoiceXMLAttr(n, "", "decimals"), Precision: invoiceXMLAttr(n, "", "precision"), Source: s, Nil: invoiceXMLAttr(n, invoiceXSI, "nil") == "true" || invoiceXMLAttr(n, invoiceXSI, "nil") == "1", Dimensions: dimensions[ref]}
+		fact := InvoiceFact{Name: n.name.Local, Namespace: n.name.Space, Value: n.text.String(), Context: ref, Unit: invoiceXMLAttr(n, "", "unitRef"), Decimals: invoiceXMLAttr(n, "", "decimals"), Precision: invoiceXMLAttr(n, "", "precision"), Source: s, Nil: invoiceXMLAttr(n, XMLSchemaInstanceNamespace, "nil") == "true" || invoiceXMLAttr(n, XMLSchemaInstanceNamespace, "nil") == "1", Dimensions: dimensions[ref]}
 		if len(n.children) > 0 {
 			fact.Value = string(n.inner)
 		}
@@ -431,8 +419,8 @@ func parseInvoiceXML(ctx context.Context, data []byte, source InvoiceSource) (In
 		}
 		inv := &report.Invoices[i]
 		inv.Facts = append(inv.Facts, fact)
-		nilValue := invoiceXMLAttr(n, invoiceXSI, "nil")
-		if invoiceXMLHasAttr(n, invoiceXSI, "nil") && nilValue != "true" && nilValue != "false" && nilValue != "1" && nilValue != "0" {
+		nilValue := invoiceXMLAttr(n, XMLSchemaInstanceNamespace, "nil")
+		if invoiceXMLHasAttr(n, XMLSchemaInstanceNamespace, "nil") && nilValue != "true" && nilValue != "false" && nilValue != "1" && nilValue != "0" {
 			issue("invalid-value", fact.Name, "invalid xsi:nil", s)
 			return nil
 		}
@@ -948,7 +936,7 @@ func invoiceMonetary(kind, name string) bool {
 	return invoiceNumeric(kind, name) && name != "QuantityOfGoodsOrServices" && name != "VatRate" && name != "TaxRate"
 }
 
-// invoiceCurrencyUnit 检查单一ISO币种度量，不猜测币种
+// invoiceCurrencyUnit 检查单一ISO币种度量
 // 入参: unit 展开的单位表示
 // 返回: 是否为三位大写币种度量
 func invoiceCurrencyUnit(unit string) bool {
@@ -1015,7 +1003,7 @@ func invoiceObjectReferences(root *invoiceXMLNode) bool {
 	count := 0
 	var walk func(*invoiceXMLNode) bool
 	walk = func(n *invoiceXMLNode) bool {
-		if n.name.Space == ofdNamespace2016 || n.name.Space == ofdNamespaceLegacy || n.name.Space == "ofd" || n.name.Space == invoiceEDRM {
+		if n.name.Space == ofdNamespace2016 || n.name.Space == ofdNamespaceLegacy || n.name.Space == "ofd" || n.name.Space == InvoiceStandardEDRM2019 {
 			if n.name.Local == "ObjectRef" {
 				count++
 				return len(n.children) == 0 && strings.TrimSpace(n.text.String()) != "" && invoiceXMLAttr(n, "", "PageRef") != ""
@@ -1052,12 +1040,12 @@ func invoicePlainXML(ctx context.Context, root *invoiceXMLNode, source InvoiceSo
 	inv := Invoice{Kind: "einv", Standard: InvoiceStandardEInvoice, Version: "0.3", Sources: []InvoiceSource{source}}
 	namespace, itemPath := "", "/EInvoice/EInvoiceData/IssuItemInformation"
 	if root.name.Local == "eInvoice" {
-		if invoiceXMLAttr(root, "", "Version") != "1.0" || len(invoiceChildren(root, invoiceEDRM, "InvoiceNo")) == 0 {
+		if invoiceXMLAttr(root, "", "Version") != "1.0" || len(invoiceChildren(root, InvoiceStandardEDRM2019, "InvoiceNo")) == 0 {
 			report.Issues = append(report.Issues, InvoiceIssue{Code: "unsupported", Message: "unsupported eInvoice namespace or version", Source: source})
 			return report, nil
 		}
-		inv.Kind, inv.Standard, inv.Version = "inv", invoiceEDRM, "1.0"
-		namespace, itemPath = invoiceEDRM, "/eInvoice/GoodsInfos/GoodsInfo"
+		inv.Kind, inv.Standard, inv.Version = "inv", InvoiceStandardEDRM2019, "1.0"
+		namespace, itemPath = InvoiceStandardEDRM2019, "/eInvoice/GoodsInfos/GoodsInfo"
 	} else {
 		headers := invoiceChildren(root, "", "Header")
 		if len(headers) != 1 {
@@ -1095,18 +1083,18 @@ func invoicePlainXML(ctx context.Context, root *invoiceXMLNode, source InvoiceSo
 		}
 		s := source
 		s.NodePath += n.path
-		f := InvoiceFact{Name: n.name.Local, Namespace: n.name.Space, Value: n.text.String(), Source: s, Nil: invoiceXMLAttr(n, invoiceXSI, "nil") == "true" || invoiceXMLAttr(n, invoiceXSI, "nil") == "1"}
+		f := InvoiceFact{Name: n.name.Local, Namespace: n.name.Space, Value: n.text.String(), Source: s, Nil: invoiceXMLAttr(n, XMLSchemaInstanceNamespace, "nil") == "true" || invoiceXMLAttr(n, XMLSchemaInstanceNamespace, "nil") == "1"}
 		inv.Facts = append(inv.Facts, f)
 		if item != nil {
 			item.Fields = append(item.Fields, f)
 		}
-		nilValue := invoiceXMLAttr(n, invoiceXSI, "nil")
-		if invoiceXMLHasAttr(n, invoiceXSI, "nil") && nilValue != "true" && nilValue != "false" && nilValue != "1" && nilValue != "0" {
+		nilValue := invoiceXMLAttr(n, XMLSchemaInstanceNamespace, "nil")
+		if invoiceXMLHasAttr(n, XMLSchemaInstanceNamespace, "nil") && nilValue != "true" && nilValue != "false" && nilValue != "1" && nilValue != "0" {
 			report.Issues = append(report.Issues, InvoiceIssue{Code: "invalid-value", Field: f.Name, Message: "invalid xsi:nil", Source: s})
 			return nil
 		}
 		dst, numeric := invoicePlainField(&inv, item, path)
-		if inv.Standard == invoiceEDRM {
+		if inv.Standard == InvoiceStandardEDRM2019 {
 			dst, numeric = invoiceEDRMField(&inv, item, path)
 		}
 		if dst == nil {
@@ -1116,7 +1104,7 @@ func invoicePlainXML(ctx context.Context, root *invoiceXMLNode, source InvoiceSo
 			report.Issues = append(report.Issues, InvoiceIssue{Code: "invalid-value", Field: f.Name, Message: "nil fact contains a value", Source: s})
 			return nil
 		}
-		if numeric && inv.Standard == invoiceEDRM && strings.TrimSpace(f.Value) == "" && !f.Nil {
+		if numeric && inv.Standard == InvoiceStandardEDRM2019 && strings.TrimSpace(f.Value) == "" && !f.Nil {
 			return nil
 		}
 		if numeric && !f.Nil && invoiceDecimal(f.Value) == nil {
@@ -1144,7 +1132,7 @@ func invoicePlainXML(ctx context.Context, root *invoiceXMLNode, source InvoiceSo
 	if err := walk(root, "", nil); err != nil {
 		return InvoiceReport{}, err
 	}
-	if inv.Standard == invoiceEDRM && inv.Date != "" {
+	if inv.Standard == InvoiceStandardEDRM2019 && inv.Date != "" {
 		if date, err := time.Parse("2006年01月02日", inv.Date); err == nil {
 			inv.Date = date.Format("2006-01-02")
 		}
diff --git a/ofdgo_render_output.go b/ofdgo_render_output.go
index 0aff578..f566494 100644
--- a/ofdgo_render_output.go
+++ b/ofdgo_render_output.go
@@ -31,8 +31,11 @@ import (
 	"golang.org/x/image/draw"
 )
 
+// xmpNamespace 表示XMP元数据命名空间
+const xmpNamespace = "http://ns.adobe.com/xap/1.0/"
+
 // creatorXMP 记录独立导出文件的制作软件
-const creatorXMP = `<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"><rdf:Description rdf:about="" xmlns:xmp="http://ns.adobe.com/xap/1.0/"><xmp:CreatorTool>` + ofdCreator + `</xmp:CreatorTool></rdf:Description></rdf:RDF>`
+const creatorXMP = `<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"><rdf:Description rdf:about="" xmlns:xmp="` + xmpNamespace + `"><xmp:CreatorTool>` + ofdCreator + `</xmp:CreatorTool></rdf:Description></rdf:RDF>`
 
 // imageMetadataWriter 在图像固定头之后插入元数据，不缓存图像主体
 type imageMetadataWriter struct {
@@ -279,7 +282,7 @@ func (r *Renderer) RenderToJPEG(page *PageContent, writer io.Writer, options *jp
 	if err != nil {
 		return err
 	}
-	metadata := []byte("http://ns.adobe.com/xap/1.0/\x00" + creatorXMP)
+	metadata := []byte(xmpNamespace + "\x00" + creatorXMP)
 	segment := make([]byte, len(metadata)+4)
 	segment[0], segment[1] = 0xff, 0xe1
 	binary.BigEndian.PutUint16(segment[2:], uint16(len(metadata)+2))
diff --git a/ofdgo_render_preview.go b/ofdgo_render_preview.go
index 798c991..77355a0 100644
--- a/ofdgo_render_preview.go
+++ b/ofdgo_render_preview.go
@@ -22,6 +22,9 @@ import (
 	"io"
 )
 
+// svgNamespace 表示SVG预览文档命名空间
+const svgNamespace = "http://www.w3.org/2000/svg"
+
 // PreviewOptions 指定页面显示方式，光栅预览不提供SVG对象分组
 type PreviewOptions struct {
 	Raster  bool
@@ -50,7 +53,7 @@ func (r *Renderer) RenderPreview(page *PageContent, writer io.Writer, options Pr
 		return SVGResources{}, err
 	}
 	name := fmt.Sprintf("ofdgo-image-%x", sha256.Sum256(pixels.Bytes()))
-	_, err = fmt.Fprintf(writer, `<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="%gmm" height="%gmm" viewBox="0 0 %g %g"><image width="%g" height="%g" preserveAspectRatio="none" xlink:href="%s"/></svg>`, box.W, box.H, box.W, box.H, box.W, box.H, name)
+	_, err = fmt.Fprintf(writer, `<svg xmlns="`+svgNamespace+`" xmlns:xlink="`+XLinkNamespace+`" width="%gmm" height="%gmm" viewBox="0 0 %g %g"><image width="%g" height="%g" preserveAspectRatio="none" xlink:href="%s"/></svg>`, box.W, box.H, box.W, box.H, box.W, box.H, name)
 	if err != nil {
 		return SVGResources{}, err
 	}
@@ -120,6 +123,6 @@ func (r *Renderer) RenderFontPreview(ctx context.Context, id string, writer io.W
 		return fmt.Errorf("font has no visible glyphs")
 	}
 	width, height := min(count, 8)*36, (count+7)/8*40
-	_, err = fmt.Fprintf(writer, `<svg xmlns="http://www.w3.org/2000/svg" width="%d" height="%d" viewBox="0 0 %d %d">%s</svg>`, width, height, width, height, paths.Bytes())
+	_, err = fmt.Fprintf(writer, `<svg xmlns="`+svgNamespace+`" width="%d" height="%d" viewBox="0 0 %d %d">%s</svg>`, width, height, width, height, paths.Bytes())
 	return err
 }
diff --git a/ofdgo_res.go b/ofdgo_res.go
index 2692da1..3cc254b 100644
--- a/ofdgo_res.go
+++ b/ofdgo_res.go
@@ -283,7 +283,7 @@ func sameResourceID(first, second string) bool {
 	return id != "" && id == editorResourceID(second)
 }
 
-// resourceValue 优先查找原标识与标准十进制标识，回退别名有冲突时不猜测
+// resourceValue 优先查找原标识与标准十进制标识，回退时检查别名冲突
 // 入参: values 已加载资源, id 标识文本
 // 返回: T 资源值, bool 是否存在唯一结果
 func resourceValue[T comparable](values map[string]T, id string) (T, bool) {
diff --git a/ofdgo_resource.go b/ofdgo_resource.go
index ca86899..972bbaf 100644
--- a/ofdgo_resource.go
+++ b/ofdgo_resource.go
@@ -394,7 +394,7 @@ func scanResourcePage(ctx context.Context, file *editorFontXML, pages map[string
 				return false, false, nil, nil
 			}
 			for _, attr := range token.Attr {
-				if attr.Name.Space != "" && attr.Name.Space != "xmlns" && attr.Name.Space != "http://www.w3.org/XML/1998/namespace" {
+				if attr.Name.Space != "" && attr.Name.Space != "xmlns" && attr.Name.Space != XMLNamespace {
 					return false, false, nil, nil
 				}
 			}
diff --git a/ofdgo_structure_xml.go b/ofdgo_structure_xml.go
index a5900c9..314398c 100644
--- a/ofdgo_structure_xml.go
+++ b/ofdgo_structure_xml.go
@@ -45,7 +45,7 @@ func encodeStructureNode(node StructureNode) ([]byte, error) {
 		switch node.Namespace {
 		case "":
 			start.Attr = append(start.Attr, xml.Attr{Name: xml.Name{Local: "xmlns"}, Value: ""})
-		case "http://www.w3.org/XML/1998/namespace":
+		case XMLNamespace:
 			start.Name = xml.Name{Local: "xml:" + node.Name}
 		}
 		for _, attr := range node.Attributes {
@@ -73,20 +73,20 @@ func encodeStructureNode(node StructureNode) ([]byte, error) {
 	return output.Bytes(), nil
 }
 
-// validateStructureNode 校验XML名称和文本，禁止重复属性及伪造命名空间声明
+// validateStructureNode 校验标引节点名称、属性和文本
 // 入参: node 节点字段
 // 返回: error 字段校验错误
 func validateStructureNode(node StructureNode) error {
 	if !ofdXMLIDValid(node.Name) || node.Name == "xmlns" {
 		return fmt.Errorf("invalid custom tag node name: %s", node.Name)
 	}
-	if !structureXMLText(node.Text) || !structureXMLText(node.Namespace) || node.Namespace == "http://www.w3.org/2000/xmlns/" {
+	if !structureXMLText(node.Text) || !structureXMLText(node.Namespace) || node.Namespace == xmlDeclarationNamespace {
 		return fmt.Errorf("invalid custom tag text or namespace")
 	}
 	seen := make(map[xml.Name]bool)
 	for _, attr := range node.Attributes {
 		name := xml.Name{Space: attr.Namespace, Local: attr.Name}
-		if !ofdXMLIDValid(attr.Name) || attr.Name == "xmlns" || attr.Namespace == "http://www.w3.org/2000/xmlns/" || !structureXMLText(attr.Namespace) || !structureXMLText(attr.Value) || seen[name] {
+		if !ofdXMLIDValid(attr.Name) || attr.Name == "xmlns" || attr.Namespace == xmlDeclarationNamespace || !structureXMLText(attr.Namespace) || !structureXMLText(attr.Value) || seen[name] {
 			return fmt.Errorf("invalid or duplicate custom tag attribute: %s", attr.Name)
 		}
 		seen[name] = true
@@ -159,7 +159,7 @@ func updateStructureNodeXML(data []byte, source *editorXML, node StructureNode)
 		if namespace == "" {
 			return name
 		}
-		if namespace == "http://www.w3.org/XML/1998/namespace" {
+		if namespace == XMLNamespace {
 			return "xml:" + name
 		}
 		for _, attr := range attrs {
diff --git a/ofdgo_xml.go b/ofdgo_xml.go
index 4a10f4c..1588ce5 100644
--- a/ofdgo_xml.go
+++ b/ofdgo_xml.go
@@ -19,6 +19,18 @@ import (
 	"unicode/utf8"
 )
 
+// XMLNamespace 表示XML预定义命名空间
+const XMLNamespace = "http://www.w3.org/XML/1998/namespace"
+
+// XMLSchemaInstanceNamespace 表示XMLSchema实例命名空间
+const XMLSchemaInstanceNamespace = "http://www.w3.org/2001/XMLSchema-instance"
+
+// XLinkNamespace 表示XML链接命名空间
+const XLinkNamespace = "http://www.w3.org/1999/xlink"
+
+// xmlDeclarationNamespace 表示XML命名空间声明标识
+const xmlDeclarationNamespace = "http://www.w3.org/2000/xmlns/"
+
 // 旧版与2016版OFD命名空间
 const (
 	ofdNamespaceLegacy = "http://www.ofdspec.org"