diff --git a/include/xlnt/xlnt_config.hpp b/include/xlnt/xlnt_config.hpp
index 718f71bb..ac8ddce8 100644
--- a/include/xlnt/xlnt_config.hpp
+++ b/include/xlnt/xlnt_config.hpp
@@ -52,7 +52,7 @@ enum class limit_style
 /// The style of limits to use for reading and writing XLSX files.
 /// See limit_style for more information.
 /// </summary>
-const limit_style LimitStyle = limit_style::openpyxl;
+const limit_style xlnt_limit_style = limit_style::openpyxl;
 
 #ifndef XLNT_API
 #if !defined(XLNT_STATIC) && defined(_MSC_VER)
diff --git a/source/cell/cell_reference.cpp b/source/cell/cell_reference.cpp
index 0cf72a2b..2982258c 100644
--- a/source/cell/cell_reference.cpp
+++ b/source/cell/cell_reference.cpp
@@ -33,7 +33,7 @@ namespace xlnt {
 
 std::size_t cell_reference_hash::operator()(const cell_reference &k) const
 {
-    return k.get_row() * constants::MaxColumn().index + k.get_column_index().index;
+    return k.get_row() * constants::max_column().index + k.get_column_index().index;
 }
 
 cell_reference &cell_reference::make_absolute(bool absolute_column, bool absolute_row)
@@ -74,7 +74,7 @@ cell_reference::cell_reference(column_t column_index, row_t row)
         throw value_error();
     }
     
-    if (!(row_ <= constants::MaxRow()) || !(column_ <= constants::MaxColumn()))
+    if (!(row_ <= constants::max_row()) || !(column_ <= constants::max_column()))
     {
         throw cell_coordinates_error(column_, row_);
     }
diff --git a/source/cell/index_types.cpp b/source/cell/index_types.cpp
index e31cf6e5..34a2c34c 100644
--- a/source/cell/index_types.cpp
+++ b/source/cell/index_types.cpp
@@ -63,7 +63,7 @@ std::string column_t::column_string_from_index(column_t::index_t column_index)
 {
     // these indicies corrospond to A->ZZZ and include all allowed
     // columns
-    if (column_index < constants::MinColumn() || column_index > constants::MaxColumn())
+    if (column_index < constants::min_column() || column_index > constants::max_column())
     {
         //        auto msg = "Column index out of bounds: " + std::to_string(column_index);
         throw column_string_index_error();
diff --git a/source/detail/constants.cpp b/source/detail/constants.cpp
index 9b60b88f..ef8857d2 100644
--- a/source/detail/constants.cpp
+++ b/source/detail/constants.cpp
@@ -28,14 +28,14 @@
 
 namespace xlnt {
 
-const row_t constants::MinRow()
+const row_t constants::min_row()
 {
     return 1;
 }
     
-const row_t constants::MaxRow()
+const row_t constants::max_row()
 {
-    if(LimitStyle == limit_style::excel)
+    if(xlnt_limit_style == limit_style::excel)
     {
         return 1u << 20;
     }
@@ -43,69 +43,67 @@ const row_t constants::MaxRow()
     return std::numeric_limits<row_t>::max();
 }
 
-const column_t constants::MinColumn()
+const column_t constants::min_column()
 {
     return column_t(1);
 }
 
-const column_t constants::MaxColumn()
+const column_t constants::max_column()
 {
-    if(LimitStyle == limit_style::excel)
+    switch (xlnt_limit_style)
     {
+    case limit_style::excel:
         return column_t(1u << 14);
+
+    case limit_style::openpyxl:
+        return column_t(18'278);
+
+    default:
+        return column_t(std::numeric_limits<column_t::index_t>::max());
     }
-    
-    if(LimitStyle == limit_style::openpyxl)
-    {
-        return column_t(18278);
-    }
-    
-    return column_t(std::numeric_limits<column_t::index_t>::max());
 }
 
 // constants
-const std::string constants::PackageProps() { return "docProps"; }
-const std::string constants::PackageXl() { return "xl"; }
-const std::string constants::PackageRels() { return "_rels"; }
-const std::string constants::PackageTheme() { return PackageXl() + "/" + "theme"; }
-const std::string constants::PackageWorksheets() { return PackageXl() + "/" + "worksheets"; }
-const std::string constants::PackageDrawings() { return PackageXl() + "/" + "drawings"; }
-const std::string constants::PackageCharts() { return PackageXl() + "/" + "charts"; }
+const std::string constants::package_properties() { return "docProps"; }
+const std::string constants::package_xl() { return "xl"; }
+const std::string constants::package_root_rels() { return "_rels"; }
+const std::string constants::package_theme() { return package_xl() + "/" + "theme"; }
+const std::string constants::package_worksheets() { return package_xl() + "/" + "worksheets"; }
 
-const std::string constants::ArcContentTypes() { return "[Content_Types].xml"; }
-const std::string constants::ArcRootRels() { return PackageRels() + "/.rels"; }
-const std::string constants::ArcWorkbookRels() { return PackageXl() + "/" + PackageRels() + "/workbook.xml.rels"; }
-const std::string constants::ArcCore() { return PackageProps() + "/core.xml"; }
-const std::string constants::ArcApp() { return PackageProps() + "/app.xml"; }
-const std::string constants::ArcWorkbook() { return PackageXl() + "/workbook.xml"; }
-const std::string constants::ArcStyles() { return PackageXl() + "/styles.xml"; }
-const std::string constants::ArcTheme() { return PackageTheme() + "/theme1.xml"; }
-const std::string constants::ArcSharedString() { return PackageXl() + "/sharedStrings.xml"; }
+const std::string constants::part_content_types() { return "[Content_Types].xml"; }
+const std::string constants::part_root_relationships() { return package_root_rels() + "/.rels"; }
+const std::string constants::part_core() { return package_properties() + "/core.xml"; }
+const std::string constants::part_app() { return package_properties() + "/app.xml"; }
+const std::string constants::part_workbook() { return package_xl() + "/workbook.xml"; }
+const std::string constants::part_styles() { return package_xl() + "/styles.xml"; }
+const std::string constants::part_theme() { return package_theme() + "/theme1.xml"; }
+const std::string constants::part_shared_strings() { return package_xl() + "/sharedStrings.xml"; }
 
-const std::unordered_map<std::string, std::string> constants::Namespaces()
+const std::unordered_map<std::string, std::string> &constants::get_namespaces()
 {
-    const std::unordered_map<std::string, std::string> namespaces =
-    {
-        { "spreadsheetml", "http://schemas.openxmlformats.org/spreadsheetml/2006/main" },
-        { "content-types", "http://schemas.openxmlformats.org/package/2006/content-types" },
-        { "relationships", "http://schemas.openxmlformats.org/package/2006/relationships" },
-        { "drawingml", "http://schemas.openxmlformats.org/drawingml/2006/main" },
-        { "r", "http://schemas.openxmlformats.org/officeDocument/2006/relationships" },
-        { "cp", "http://schemas.openxmlformats.org/package/2006/metadata/core-properties" },
-        { "dc", "http://purl.org/dc/elements/1.1/" },
-        { "dcterms", "http://purl.org/dc/terms/" },
-        { "dcmitype", "http://purl.org/dc/dcmitype/" },
-        { "xsi", "http://www.w3.org/2001/XMLSchema-instance" },
-        { "vt", "http://schemas.openxmlformats.org/officeDocument/2006/docPropsVTypes" },
-        { "xml", "http://www.w3.org/XML/1998/namespace" }
-    };
-    
-    return namespaces;
+    const std::unordered_map<std::string, std::string> *namespaces =
+        new std::unordered_map<std::string, std::string>
+        {
+            { "spreadsheetml", "http://schemas.openxmlformats.org/spreadsheetml/2006/main" },
+            { "content-types", "http://schemas.openxmlformats.org/package/2006/content-types" },
+            { "relationships", "http://schemas.openxmlformats.org/package/2006/relationships" },
+            { "drawingml", "http://schemas.openxmlformats.org/drawingml/2006/main" },
+            { "r", "http://schemas.openxmlformats.org/officeDocument/2006/relationships" },
+            { "cp", "http://schemas.openxmlformats.org/package/2006/metadata/core-properties" },
+            { "dc", "http://purl.org/dc/elements/1.1/" },
+            { "dcterms", "http://purl.org/dc/terms/" },
+            { "dcmitype", "http://purl.org/dc/dcmitype/" },
+            { "xsi", "http://www.w3.org/2001/XMLSchema-instance" },
+            { "vt", "http://schemas.openxmlformats.org/officeDocument/2006/docPropsVTypes" },
+            { "xml", "http://www.w3.org/XML/1998/namespace" }
+        };
+
+    return *namespaces;
 }
 
-const std::string constants::Namespace(const std::string &id)
+const std::string constants::get_namespace(const std::string &id)
 {
-    return Namespaces().find(id)->second;
+    return get_namespaces().find(id)->second;
 }
 
 }
diff --git a/source/detail/constants.hpp b/source/detail/constants.hpp
index e31b814d..432752c9 100644
--- a/source/detail/constants.hpp
+++ b/source/detail/constants.hpp
@@ -31,33 +31,100 @@ namespace xlnt {
 
 struct constants
 {
-    static const row_t MinRow();
-    static const row_t MaxRow();
-    static const column_t MinColumn();
-    static const column_t MaxColumn();
+    /// <summary>
+    /// Returns the lowest allowable row index in a worksheet.
+    /// </summary>
+    static const row_t min_row();
 
-    // constants
-    static const std::string PackageProps();
-    static const std::string PackageXl();
-    static const std::string PackageRels();
-    static const std::string PackageTheme();
-    static const std::string PackageWorksheets();
-    static const std::string PackageDrawings();
-    static const std::string PackageCharts();
+    /// <summary>
+    /// Returns the largest allowable row index in a worksheet.
+    /// </summary>
+    static const row_t max_row();
 
-    static const std::string ArcContentTypes();
-    static const std::string ArcRootRels();
-    static const std::string ArcWorkbookRels();
-    static const std::string ArcCore();
-    static const std::string ArcApp();
-    static const std::string ArcWorkbook();
-    static const std::string ArcStyles();
-    static const std::string ArcTheme();
-    static const std::string ArcSharedString();
+    /// <summary>
+    /// Returns the lowest allowable column index in a worksheet.
+    /// </summary>
+    static const column_t min_column();
 
-    static const std::unordered_map<std::string, std::string> Namespaces();
-    
-    static const std::string Namespace(const std::string &id);
+    /// <summary>
+    /// Returns the largest allowable column index in a worksheet.
+    /// </summary>
+    static const column_t max_column();
+
+    /// <summary>
+    /// Returns the URI of the directory containing package properties.
+    /// </summary>
+    static const std::string package_properties();
+
+    /// <summary>
+    /// Returns the URI of the directory containing SpreatsheetML package parts.
+    /// </summary>
+    static const std::string package_xl();
+
+    /// <summary>
+    /// Returns the URI of the directory containing root relationships package part.
+    /// </summary>
+    static const std::string package_root_rels();
+
+    /// <summary>
+    /// Returns the URI of the directory containing package themes.
+    /// </summary>
+    static const std::string package_theme();
+
+    /// <summary>
+    /// Returns the URI of the directory containing package worksheets.
+    /// </summary>
+    static const std::string package_worksheets();
+
+    /// <summary>
+    /// Returns the URI of the content types package part.
+    /// </summary>
+    static const std::string part_content_types();
+
+    /// <summary>
+    /// Returns the URI of the core properties package part.
+    /// </summary>
+    static const std::string part_core();
+
+    /// <summary>
+    /// Returns the URI of the app properties package part.
+    /// </summary>
+    static const std::string part_app();
+
+    /// <summary>
+    /// Returns the URI of the workbook package part.
+    /// </summary>
+    static const std::string part_workbook();
+
+    /// <summary>
+    /// Returns the URI of the root relationships package part.
+    /// </summary>
+    static const std::string part_root_relationships();
+
+    /// <summary>
+    /// Returns the URI of the styles package part.
+    /// </summary>
+    static const std::string part_styles();
+
+    /// <summary>
+    /// Returns the URI of the theme package part.
+    /// </summary>
+    static const std::string part_theme();
+
+    /// <summary>
+    /// Returns the URI of the shared strings package part.
+    /// </summary>
+    static const std::string part_shared_strings();
+
+    /// <summary>
+    /// Returns an unordered_map mapping namespace names to namespaces.
+    /// </summary>
+    static const std::unordered_map<std::string, std::string> &get_namespaces();
+
+    /// <summary>
+    /// Returns the namespace URI from a namespace name.
+    /// </summary>
+    static const std::string get_namespace(const std::string &id);
 };
 
 } // namespace xlnt
diff --git a/source/detail/excel_serializer.cpp b/source/detail/excel_serializer.cpp
index 0410f900..ce11d44c 100644
--- a/source/detail/excel_serializer.cpp
+++ b/source/detail/excel_serializer.cpp
@@ -71,14 +71,14 @@ bool load_workbook(xlnt::zip_file &archive, bool guess_types, bool data_only, xl
     wb.set_guess_types(guess_types);
     wb.set_data_only(data_only);
 
-    if(!archive.has_file(xlnt::constants::ArcContentTypes()))
+    if(!archive.has_file(xlnt::constants::part_content_types()))
     {
         throw xlnt::invalid_file_error("missing [Content Types].xml");
     }
     
     xlnt::manifest_serializer ms(wb.get_manifest());
 	pugi::xml_document manifest_xml;
-    manifest_xml.load(archive.read(xlnt::constants::ArcContentTypes()).c_str());
+    manifest_xml.load(archive.read(xlnt::constants::part_content_types()).c_str());
     ms.read_manifest(manifest_xml);
 
     if (ms.determine_document_type() != "excel")
@@ -88,19 +88,19 @@ bool load_workbook(xlnt::zip_file &archive, bool guess_types, bool data_only, xl
 
     wb.clear();
     
-    if(archive.has_file(xlnt::constants::ArcCore()))
+    if(archive.has_file(xlnt::constants::part_core()))
     {
         xlnt::workbook_serializer workbook_serializer_(wb);
 		pugi::xml_document core_properties_xml;
-		core_properties_xml.load(archive.read(xlnt::constants::ArcCore()).c_str());
+		core_properties_xml.load(archive.read(xlnt::constants::part_core()).c_str());
         workbook_serializer_.read_properties_core(core_properties_xml);
     }
     
-    if(archive.has_file(xlnt::constants::ArcApp()))
+    if(archive.has_file(xlnt::constants::part_app()))
     {
         xlnt::workbook_serializer workbook_serializer_(wb);
 		pugi::xml_document app_properties_xml;
-		app_properties_xml.load(archive.read(xlnt::constants::ArcApp()).c_str());
+		app_properties_xml.load(archive.read(xlnt::constants::part_app()).c_str());
         workbook_serializer_.read_properties_app(app_properties_xml);
     }
 
@@ -112,7 +112,7 @@ bool load_workbook(xlnt::zip_file &archive, bool guess_types, bool data_only, xl
         wb.create_root_relationship(relationship.get_id(), relationship.get_target_uri(), relationship.get_type());
     }
     
-    auto workbook_relationships = relationship_serializer_.read_relationships(xlnt::constants::ArcWorkbook());
+    auto workbook_relationships = relationship_serializer_.read_relationships(xlnt::constants::part_workbook());
 
     for (const auto &relationship : workbook_relationships)
     {
@@ -120,7 +120,7 @@ bool load_workbook(xlnt::zip_file &archive, bool guess_types, bool data_only, xl
     }
 
 	pugi::xml_document xml;
-    xml.load(archive.read(xlnt::constants::ArcWorkbook()).c_str());
+    xml.load(archive.read(xlnt::constants::part_workbook()).c_str());
 
     auto root_node = xml.child("workbook");
 
@@ -130,11 +130,11 @@ bool load_workbook(xlnt::zip_file &archive, bool guess_types, bool data_only, xl
             ? xlnt::calendar::mac_1904
             : xlnt::calendar::windows_1900;
 
-    if(archive.has_file(xlnt::constants::ArcSharedString()))
+    if(archive.has_file(xlnt::constants::part_shared_strings()))
     {
         std::vector<xlnt::text> shared_strings;
 		pugi::xml_document shared_strings_xml;
-		shared_strings_xml.load(archive.read(xlnt::constants::ArcSharedString()).c_str());
+		shared_strings_xml.load(archive.read(xlnt::constants::part_shared_strings()).c_str());
 		xlnt::shared_strings_serializer::read_shared_strings(shared_strings_xml, shared_strings);
 
         for (auto &shared_string : shared_strings)
@@ -145,7 +145,7 @@ bool load_workbook(xlnt::zip_file &archive, bool guess_types, bool data_only, xl
 
     xlnt::style_serializer style_serializer(stylesheet);
 	pugi::xml_document style_xml;
-	style_xml.load(archive.read(xlnt::constants::ArcStyles()).c_str());
+	style_xml.load(archive.read(xlnt::constants::part_styles()).c_str());
     style_serializer.read_stylesheet(style_xml);
 
     auto sheets_node = root_node.child("sheets");
@@ -243,7 +243,7 @@ void excel_serializer::write_data(bool /*as_template*/)
 {
     relationship_serializer relationship_serializer_(archive_);
     relationship_serializer_.write_relationships(workbook_.get_root_relationships(), "");
-    relationship_serializer_.write_relationships(workbook_.get_relationships(), constants::ArcWorkbook());
+    relationship_serializer_.write_relationships(workbook_.get_relationships(), constants::part_workbook());
 
     pugi::xml_document properties_app_xml;
     workbook_serializer workbook_serializer_(workbook_);
@@ -252,7 +252,7 @@ void excel_serializer::write_data(bool /*as_template*/)
     {
         std::ostringstream ss;
         properties_app_xml.save(ss);
-        archive_.writestr(constants::ArcApp(), ss.str());
+        archive_.writestr(constants::part_app(), ss.str());
     }
 
     pugi::xml_document properties_core_xml;
@@ -261,7 +261,7 @@ void excel_serializer::write_data(bool /*as_template*/)
     {
         std::ostringstream ss;
         properties_core_xml.save(ss);
-        archive_.writestr(constants::ArcCore(), ss.str());
+        archive_.writestr(constants::part_core(), ss.str());
     }
 
     pugi::xml_document theme_xml;
@@ -271,7 +271,7 @@ void excel_serializer::write_data(bool /*as_template*/)
     {
         std::ostringstream ss;
         theme_xml.save(ss);
-        archive_.writestr(constants::ArcTheme(), ss.str());
+        archive_.writestr(constants::part_theme(), ss.str());
     }
 
     if (!workbook_.get_shared_strings().empty())
@@ -282,7 +282,7 @@ void excel_serializer::write_data(bool /*as_template*/)
 
         std::ostringstream ss;
         shared_strings_xml.save(ss);
-        archive_.writestr(constants::ArcSharedString(), ss.str());
+        archive_.writestr(constants::part_shared_strings(), ss.str());
     }
 
     pugi::xml_document workbook_xml;
@@ -291,7 +291,7 @@ void excel_serializer::write_data(bool /*as_template*/)
     {
         std::ostringstream ss;
         workbook_xml.save(ss);
-        archive_.writestr(constants::ArcWorkbook(), ss.str());
+        archive_.writestr(constants::part_workbook(), ss.str());
     }
 
     style_serializer style_serializer(workbook_.d_->stylesheet_);
@@ -301,7 +301,7 @@ void excel_serializer::write_data(bool /*as_template*/)
     {
         std::ostringstream ss;
         style_xml.save(ss);
-        archive_.writestr(constants::ArcStyles(), ss.str());
+        archive_.writestr(constants::part_styles(), ss.str());
     }
 
     manifest_serializer manifest_serializer_(workbook_.get_manifest());
@@ -311,7 +311,7 @@ void excel_serializer::write_data(bool /*as_template*/)
     {
         std::ostringstream ss;
         manifest_xml.save(ss);
-        archive_.writestr(constants::ArcContentTypes(), ss.str());
+        archive_.writestr(constants::part_content_types(), ss.str());
     }
 
     write_worksheets();
diff --git a/source/detail/manifest_serializer.cpp b/source/detail/manifest_serializer.cpp
index e3155461..769f9d30 100644
--- a/source/detail/manifest_serializer.cpp
+++ b/source/detail/manifest_serializer.cpp
@@ -54,7 +54,7 @@ void manifest_serializer::read_manifest(const pugi::xml_document &xml)
 void manifest_serializer::write_manifest(pugi::xml_document &xml) const
 {
     auto root_node = xml.append_child("Types");
-    root_node.append_attribute("xmlns").set_value(constants::Namespace("content-types").c_str());
+    root_node.append_attribute("xmlns").set_value(constants::get_namespace("content-types").c_str());
 
     for (const auto default_type : manifest_.get_default_types())
     {
@@ -73,12 +73,12 @@ void manifest_serializer::write_manifest(pugi::xml_document &xml) const
 
 std::string manifest_serializer::determine_document_type() const
 {
-    if (!manifest_.has_override_type(constants::ArcWorkbook()))
+    if (!manifest_.has_override_type(constants::part_workbook()))
     {
         return "unsupported";
     }
 
-    std::string type = manifest_.get_override_type(constants::ArcWorkbook());
+    std::string type = manifest_.get_override_type(constants::part_workbook());
 
     if (type == "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet.main+xml")
     {
diff --git a/source/detail/relationship_serializer.cpp b/source/detail/relationship_serializer.cpp
index a2dc0a2c..eb2bb94b 100644
--- a/source/detail/relationship_serializer.cpp
+++ b/source/detail/relationship_serializer.cpp
@@ -36,16 +36,16 @@ std::string make_rels_name(const std::string &target)
 {
     const char sep = '/';
 
-    if (target.empty() || target.back() == sep)
+    if (target.empty())
     {
-        return target + "_rels/.rels";
+        return xlnt::constants::part_root_relationships();
     }
 
     auto sep_pos = target.find_last_of(sep);
-    auto first_part = target.substr(0, sep_pos + 1);
-    auto last_part = target.substr(sep_pos + 1);
+    auto path = target.substr(0, sep_pos + 1);
+    auto filename = target.substr(sep_pos + 1);
 
-    return first_part + "_rels/" + last_part + ".rels";
+    return path + "_rels/" + filename + ".rels";
 }
 }
 
@@ -83,7 +83,7 @@ bool relationship_serializer::write_relationships(const std::vector<relationship
 
     auto root_node = xml.append_child("Relationships");
 
-    root_node.append_attribute("xmlns").set_value(constants::Namespace("relationships").c_str());
+    root_node.append_attribute("xmlns").set_value(constants::get_namespace("relationships").c_str());
 
     for (const auto &relationship : relationships)
     {
diff --git a/source/detail/theme_serializer.cpp b/source/detail/theme_serializer.cpp
index 09fec306..6df36000 100644
--- a/source/detail/theme_serializer.cpp
+++ b/source/detail/theme_serializer.cpp
@@ -34,7 +34,7 @@ namespace xlnt {
 void theme_serializer::write_theme(const theme &, pugi::xml_document &xml) const
 {
     auto theme_node = xml.append_child("a:theme");
-    theme_node.append_attribute("xmlns:a").set_value(constants::Namespace("drawingml").c_str());
+    theme_node.append_attribute("xmlns:a").set_value(constants::get_namespace("drawingml").c_str());
     theme_node.append_attribute("name").set_value("Office Theme");
 
     auto theme_elements_node = theme_node.append_child("a:themeElements");
diff --git a/source/detail/worksheet_serializer.cpp b/source/detail/worksheet_serializer.cpp
index a6bd1e73..de47e0a7 100644
--- a/source/detail/worksheet_serializer.cpp
+++ b/source/detail/worksheet_serializer.cpp
@@ -226,8 +226,8 @@ void worksheet_serializer::write_worksheet(pugi::xml_document &xml) const
 {
     auto root_node = xml.append_child("worksheet");
 
-    root_node.append_attribute("xmlns").set_value(constants::Namespace("spreadsheetml").c_str());
-    root_node.append_attribute("xmlns:r").set_value(constants::Namespace("r").c_str());
+    root_node.append_attribute("xmlns").set_value(constants::get_namespace("spreadsheetml").c_str());
+    root_node.append_attribute("xmlns:r").set_value(constants::get_namespace("r").c_str());
 
     auto sheet_pr_node = root_node.append_child("sheetPr");
 
diff --git a/source/workbook/workbook.cpp b/source/workbook/workbook.cpp
index 72a446e6..bb4f2ce8 100644
--- a/source/workbook/workbook.cpp
+++ b/source/workbook/workbook.cpp
@@ -28,6 +28,12 @@
 #include <set>
 #include <sstream>
 
+#include <detail/cell_impl.hpp>
+#include <detail/constants.hpp>
+#include <detail/excel_serializer.hpp>
+#include <detail/include_windows.hpp>
+#include <detail/workbook_impl.hpp>
+#include <detail/worksheet_impl.hpp>
 #include <xlnt/packaging/app_properties.hpp>
 #include <xlnt/packaging/document_properties.hpp>
 #include <xlnt/packaging/manifest.hpp>
@@ -50,12 +56,6 @@
 #include <xlnt/worksheet/range.hpp>
 #include <xlnt/worksheet/worksheet.hpp>
 
-#include <detail/cell_impl.hpp>
-#include <detail/excel_serializer.hpp>
-#include <detail/include_windows.hpp>
-#include <detail/workbook_impl.hpp>
-#include <detail/worksheet_impl.hpp>
-
 namespace xlnt {
 namespace detail {
 
@@ -79,11 +79,11 @@ workbook::workbook() : d_(new detail::workbook_impl())
     d_->manifest_.add_default_type("rels", "application/vnd.openxmlformats-package.relationships+xml");
     d_->manifest_.add_default_type("xml", "application/xml");
     
-    d_->manifest_.add_override_type("/xl/workbook.xml", "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet.main+xml");
-    d_->manifest_.add_override_type("/xl/theme/theme1.xml", "application/vnd.openxmlformats-officedocument.theme+xml");
-    d_->manifest_.add_override_type("/xl/styles.xml", "application/vnd.openxmlformats-officedocument.spreadsheetml.styles+xml");
-    d_->manifest_.add_override_type("/docProps/core.xml", "application/vnd.openxmlformats-package.core-properties+xml");
-    d_->manifest_.add_override_type("/docProps/app.xml", "application/vnd.openxmlformats-officedocument.extended-properties+xml");
+    d_->manifest_.add_override_type("/" + constants::part_workbook(), "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet.main+xml");
+    d_->manifest_.add_override_type("/" + constants::part_theme(), "application/vnd.openxmlformats-officedocument.theme+xml");
+    d_->manifest_.add_override_type("/" + constants::part_styles(), "application/vnd.openxmlformats-officedocument.spreadsheetml.styles+xml");
+    d_->manifest_.add_override_type("/" + constants::part_core(), "application/vnd.openxmlformats-package.core-properties+xml");
+    d_->manifest_.add_override_type("/" + constants::part_app(), "application/vnd.openxmlformats-officedocument.extended-properties+xml");
     
     add_format(format());
     create_style("Normal");
@@ -692,10 +692,11 @@ const std::vector<relationship> &workbook::get_root_relationships() const
     if (d_->root_relationships_.empty())
     {
         d_->root_relationships_.push_back(
-            relationship(relationship::type::core_properties, "rId1", "docProps/core.xml"));
+            relationship(relationship::type::core_properties, "rId1", constants::part_core()));
         d_->root_relationships_.push_back(
-            relationship(relationship::type::extended_properties, "rId2", "docProps/app.xml"));
-        d_->root_relationships_.push_back(relationship(relationship::type::office_document, "rId3", "xl/workbook.xml"));
+            relationship(relationship::type::extended_properties, "rId2", constants::part_app()));
+        d_->root_relationships_.push_back(
+            relationship(relationship::type::office_document, "rId3", constants::part_workbook()));
     }
 
     return d_->root_relationships_;
@@ -716,9 +717,9 @@ void workbook::add_shared_string(const text &shared, bool allow_duplicates)
     if (d_->shared_strings_.empty())
     {
         create_relationship(next_relationship_id(), "sharedStrings.xml", relationship::type::shared_strings);
-        d_->manifest_.add_override_type("/xl/sharedStrings.xml", "application/vnd.openxmlformats-officedocument.spreadsheetml.sharedStrings+xml");
+        d_->manifest_.add_override_type("/" + constants::part_shared_strings(), "application/vnd.openxmlformats-officedocument.spreadsheetml.sharedStrings+xml");
     }
-    
+
 	if (!allow_duplicates)
 	{
 		//TODO: inefficient, use a set or something?
diff --git a/source/worksheet/tests/test_worksheet.hpp b/source/worksheet/tests/test_worksheet.hpp
index 44128e73..cb47a2eb 100644
--- a/source/worksheet/tests/test_worksheet.hpp
+++ b/source/worksheet/tests/test_worksheet.hpp
@@ -1167,6 +1167,12 @@ public:
                 }
             }
         }
+
+        auto const_range = ws_const.get_range("B3:C7");
+        auto const_range_iter = const_range.begin();
+        const_range_iter++;
+        const_range_iter--;
+        TS_ASSERT_EQUALS(const_range_iter, const_range.begin());
     }
 
     void test_range_reference()
diff --git a/source/worksheet/worksheet.cpp b/source/worksheet/worksheet.cpp
index f0129a68..8f3a5fd9 100644
--- a/source/worksheet/worksheet.cpp
+++ b/source/worksheet/worksheet.cpp
@@ -337,10 +337,10 @@ column_t worksheet::get_lowest_column() const
 {
     if (d_->cell_map_.empty())
     {
-        return constants::MinColumn();
+        return constants::min_column();
     }
 
-    column_t lowest = constants::MaxColumn();
+    column_t lowest = constants::max_column();
 
     for (auto &row : d_->cell_map_)
     {
@@ -357,10 +357,10 @@ row_t worksheet::get_lowest_row() const
 {
     if (d_->cell_map_.empty())
     {
-        return constants::MinRow();
+        return constants::min_row();
     }
 
-    row_t lowest = constants::MaxRow();
+    row_t lowest = constants::max_row();
 
     for (auto &row : d_->cell_map_)
     {
@@ -372,7 +372,7 @@ row_t worksheet::get_lowest_row() const
 
 row_t worksheet::get_highest_row() const
 {
-    row_t highest = constants::MinRow();
+    row_t highest = constants::min_row();
 
     for (auto &row : d_->cell_map_)
     {
@@ -384,7 +384,7 @@ row_t worksheet::get_highest_row() const
 
 column_t worksheet::get_highest_column() const
 {
-    column_t highest = constants::MinColumn();
+    column_t highest = constants::min_column();
 
     for (auto &row : d_->cell_map_)
     {