diff --git a/src/base/component/block.rs b/src/base/component/block.rs
index 9ffe986d..4f658c9e 100644
--- a/src/base/component/block.rs
+++ b/src/base/component/block.rs
@@ -4,7 +4,7 @@ pub struct Block {
     renderable: fn() -> bool,
     weight    : i8,
     id        : Option<String>,
-    title     : String,
+    title     : Option<String>,
     markup    : Vec<Markup>,
     template  : String,
 }
@@ -16,9 +16,9 @@ impl PageComponent for Block {
             renderable: always,
             weight    : 0,
             id        : None,
-            title     : "".to_string(),
+            title     : None,
             markup    : Vec::new(),
-            template  : "default".to_string(),
+            template  : "default".to_owned(),
         }
     }
 
@@ -34,8 +34,8 @@ impl PageComponent for Block {
         let id = assets.serial_id(self.name(), self.id());
         html! {
             div id=(id) class="block" {
-                @if !self.title.is_empty() {
-                    h2 class="block-title" { (self.title) }
+                @if self.title != None {
+                    h2 class="block-title" { (self.title()) }
                 }
                 div class="block-body" {
                     @for markup in self.markup.iter() {
@@ -71,7 +71,7 @@ impl Block {
     }
 
     pub fn with_title(mut self, title: &str) -> Self {
-        self.title = title.to_string();
+        self.title = util::optional_str(title);
         self
     }
 
@@ -81,18 +81,18 @@ impl Block {
     }
 
     pub fn using_template(mut self, template: &str) -> Self {
-        self.template = template.to_string();
+        self.template = template.to_owned();
         self
     }
 
     // Block GETTERS.
 
     pub fn id(&self) -> &str {
-        util::assigned_value(&self.id)
+        util::assigned_str(&self.id)
     }
 
     pub fn title(&self) -> &str {
-        self.title.as_str()
+        util::assigned_str(&self.title)
     }
 
     pub fn template(&self) -> &str {
diff --git a/src/base/component/chunck.rs b/src/base/component/chunck.rs
index 8d4e956f..63cc20f7 100644
--- a/src/base/component/chunck.rs
+++ b/src/base/component/chunck.rs
@@ -14,7 +14,7 @@ impl PageComponent for Chunck {
             renderable: always,
             weight    : 0,
             markup    : Vec::new(),
-            template  : "default".to_string(),
+            template  : "default".to_owned(),
         }
     }
 
@@ -59,7 +59,7 @@ impl Chunck {
     }
 
     pub fn using_template(mut self, template: &str) -> Self {
-        self.template = template.to_string();
+        self.template = template.to_owned();
         self
     }
 
diff --git a/src/base/component/container.rs b/src/base/component/container.rs
index 61c08336..161bea78 100644
--- a/src/base/component/container.rs
+++ b/src/base/component/container.rs
@@ -20,7 +20,7 @@ impl PageComponent for Container {
             id        : None,
             container : ContainerType::Wrapper,
             components: PageContainer::new(),
-            template  : "default".to_string(),
+            template  : "default".to_owned(),
         }
     }
 
@@ -83,14 +83,14 @@ impl Container {
     }
 
     pub fn using_template(mut self, template: &str) -> Self {
-        self.template = template.to_string();
+        self.template = template.to_owned();
         self
     }
 
     // Container GETTERS.
 
     pub fn id(&self) -> &str {
-        util::assigned_value(&self.id)
+        util::assigned_str(&self.id)
     }
 
     pub fn template(&self) -> &str {
diff --git a/src/base/component/form/button.rs b/src/base/component/form/button.rs
index c95eb3ec..c76c49dd 100644
--- a/src/base/component/form/button.rs
+++ b/src/base/component/form/button.rs
@@ -24,7 +24,7 @@ impl PageComponent for Button {
             value      : None,
             autofocus  : None,
             disabled   : None,
-            template   : "default".to_string(),
+            template   : "default".to_owned(),
         }
     }
 
@@ -101,13 +101,13 @@ impl Button {
     }
 
     pub fn with_value(mut self, value: &str) -> Self {
-        self.value = util::optional_value(value);
+        self.value = util::optional_str(value);
         self
     }
 
     pub fn autofocus(mut self, toggle: bool) -> Self {
         self.autofocus = match toggle {
-            true => Some("autofocus".to_string()),
+            true => Some("autofocus".to_owned()),
             false => None
         };
         self
@@ -115,25 +115,25 @@ impl Button {
 
     pub fn disabled(mut self, toggle: bool) -> Self {
         self.disabled = match toggle {
-            true => Some("disabled".to_string()),
+            true => Some("disabled".to_owned()),
             false => None
         };
         self
     }
 
     pub fn using_template(mut self, template: &str) -> Self {
-        self.template = template.to_string();
+        self.template = template.to_owned();
         self
     }
 
     // Button GETTERS.
 
     pub fn name(&self) -> &str {
-        util::assigned_value(&self.name)
+        util::assigned_str(&self.name)
     }
 
     pub fn value(&self) -> &str {
-        util::assigned_value(&self.value)
+        util::assigned_str(&self.value)
     }
 
     pub fn has_autofocus(&self) -> bool {
diff --git a/src/base/component/form/date.rs b/src/base/component/form/date.rs
index b2839e8e..ccc6ab31 100644
--- a/src/base/component/form/date.rs
+++ b/src/base/component/form/date.rs
@@ -5,14 +5,14 @@ pub struct Date {
     weight      : i8,
     name        : Option<String>,
     value       : Option<String>,
-    label       : String,
+    label       : Option<String>,
     placeholder : Option<String>,
     autofocus   : Option<String>,
     autocomplete: Option<String>,
     disabled    : Option<String>,
     readonly    : Option<String>,
     required    : Option<String>,
-    help_text   : String,
+    help_text   : Option<String>,
     template    : String,
 }
 
@@ -24,15 +24,15 @@ impl PageComponent for Date {
             weight      : 0,
             name        : None,
             value       : None,
-            label       : "".to_string(),
+            label       : None,
             placeholder : None,
             autofocus   : None,
             autocomplete: None,
             disabled    : None,
             readonly    : None,
             required    : None,
-            help_text   : "".to_string(),
-            template    : "default".to_string(),
+            help_text   : None,
+            template    : "default".to_owned(),
         }
     }
 
@@ -51,15 +51,15 @@ impl PageComponent for Date {
                 Some(format!("edit-{}", name))
             ),
             None => (
-                "form-item form-type-date".to_string(),
+                "form-item form-type-date".to_owned(),
                 None
             )
         };
         html! {
             div class=(class_item) {
-                @if !self.label.is_empty() {
+                @if self.label != None {
                     label class="form-label" for=[&id_item] {
-                        (self.label) " "
+                        (self.label()) " "
                         @if self.required != None {
                             span
                                 class="form-required"
@@ -82,9 +82,9 @@ impl PageComponent for Date {
                     readonly=[&self.readonly]
                     required=[&self.required]
                     disabled=[&self.disabled];
-                @if !self.help_text.is_empty() {
+                @if self.help_text != None {
                     div class="form-text" {
-                        (self.help_text)
+                        (self.help_text())
                     }
                 }
             }
@@ -112,23 +112,23 @@ impl Date {
     }
 
     pub fn with_value(mut self, value: &str) -> Self {
-        self.value = util::optional_value(value);
+        self.value = util::optional_str(value);
         self
     }
 
     pub fn with_label(mut self, label: &str) -> Self {
-        self.label = label.to_string();
+        self.label = util::optional_str(label);
         self
     }
 
     pub fn with_placeholder(mut self, placeholder: &str) -> Self {
-        self.placeholder = util::optional_value(placeholder);
+        self.placeholder = util::optional_str(placeholder);
         self
     }
 
     pub fn autofocus(mut self, toggle: bool) -> Self {
         self.autofocus = match toggle {
-            true => Some("autofocus".to_string()),
+            true => Some("autofocus".to_owned()),
             false => None
         };
         self
@@ -137,14 +137,14 @@ impl Date {
     pub fn autocomplete(mut self, toggle: bool) -> Self {
         self.autocomplete = match toggle {
             true => None,
-            false => Some("off".to_string())
+            false => Some("off".to_owned())
         };
         self
     }
 
     pub fn disabled(mut self, toggle: bool) -> Self {
         self.disabled = match toggle {
-            true => Some("disabled".to_string()),
+            true => Some("disabled".to_owned()),
             false => None
         };
         self
@@ -152,7 +152,7 @@ impl Date {
 
     pub fn readonly(mut self, toggle: bool) -> Self {
         self.readonly = match toggle {
-            true => Some("readonly".to_string()),
+            true => Some("readonly".to_owned()),
             false => None
         };
         self
@@ -160,38 +160,38 @@ impl Date {
 
     pub fn required(mut self, toggle: bool) -> Self {
         self.required = match toggle {
-            true => Some("required".to_string()),
+            true => Some("required".to_owned()),
             false => None
         };
         self
     }
 
     pub fn with_help_text(mut self, help_text: &str) -> Self {
-        self.help_text = help_text.to_string();
+        self.help_text = util::optional_str(help_text);
         self
     }
 
     pub fn using_template(mut self, template: &str) -> Self {
-        self.template = template.to_string();
+        self.template = template.to_owned();
         self
     }
 
     // Date GETTERS.
 
     pub fn name(&self) -> &str {
-        util::assigned_value(&self.name)
+        util::assigned_str(&self.name)
     }
 
     pub fn value(&self) -> &str {
-        util::assigned_value(&self.value)
+        util::assigned_str(&self.value)
     }
 
     pub fn label(&self) -> &str {
-        self.label.as_str()
+        util::assigned_str(&self.label)
     }
 
     pub fn placeholder(&self) -> &str {
-        util::assigned_value(&self.placeholder)
+        util::assigned_str(&self.placeholder)
     }
 
     pub fn has_autofocus(&self) -> bool {
@@ -230,7 +230,7 @@ impl Date {
     }
 
     pub fn help_text(&self) -> &str {
-        self.help_text.as_str()
+        util::assigned_str(&self.help_text)
     }
 
     pub fn template(&self) -> &str {
diff --git a/src/base/component/form/form.rs b/src/base/component/form/form.rs
index 6f73469d..63eace0c 100644
--- a/src/base/component/form/form.rs
+++ b/src/base/component/form/form.rs
@@ -22,9 +22,9 @@ impl PageComponent for Form {
             id        : None,
             action    : None,
             method    : FormMethod::Post,
-            charset   : Some("UTF-8".to_string()),
+            charset   : Some("UTF-8".to_owned()),
             elements  : PageContainer::new(),
-            template  : "default".to_string(),
+            template  : "default".to_owned(),
         }
     }
 
@@ -39,7 +39,7 @@ impl PageComponent for Form {
     fn default_render(&self, assets: &mut PageAssets) -> Markup {
         let method = match self.method {
             FormMethod::Get => None,
-            FormMethod::Post => Some("post".to_string())
+            FormMethod::Post => Some("post".to_owned())
         };
         html! {
             form
@@ -76,7 +76,7 @@ impl Form {
     }
 
     pub fn with_action(mut self, action: &str) -> Self {
-        self.action = util::optional_value(action);
+        self.action = util::optional_str(action);
         self
     }
 
@@ -86,7 +86,7 @@ impl Form {
     }
 
     pub fn with_charset(mut self, charset: &str) -> Self {
-        self.charset = util::optional_value(charset);
+        self.charset = util::optional_str(charset);
         self
     }
 
@@ -96,18 +96,18 @@ impl Form {
     }
 
     pub fn using_template(mut self, template: &str) -> Self {
-        self.template = template.to_string();
+        self.template = template.to_owned();
         self
     }
 
     // Form GETTERS.
 
     pub fn id(&self) -> &str {
-        util::assigned_value(&self.id)
+        util::assigned_str(&self.id)
     }
 
     pub fn action(&self) -> &str {
-        util::assigned_value(&self.action)
+        util::assigned_str(&self.action)
     }
 
     pub fn method(&self) -> &str {
@@ -118,7 +118,7 @@ impl Form {
     }
 
     pub fn charset(&self) -> &str {
-        util::assigned_value(&self.charset)
+        util::assigned_str(&self.charset)
     }
 
     pub fn template(&self) -> &str {
diff --git a/src/base/component/form/hidden.rs b/src/base/component/form/hidden.rs
index 57b4b34f..9ac0a4f9 100644
--- a/src/base/component/form/hidden.rs
+++ b/src/base/component/form/hidden.rs
@@ -54,17 +54,17 @@ impl Hidden {
     }
 
     pub fn with_value(mut self, value: &str) -> Self {
-        self.value = util::optional_value(value);
+        self.value = util::optional_str(value);
         self
     }
 
     // Hidden GETTERS.
 
     pub fn name(&self) -> &str {
-        util::assigned_value(&self.name)
+        util::assigned_str(&self.name)
     }
 
     pub fn value(&self) -> &str {
-        util::assigned_value(&self.value)
+        util::assigned_str(&self.value)
     }
 }
diff --git a/src/base/component/form/input.rs b/src/base/component/form/input.rs
index 82c0bda3..884d2232 100644
--- a/src/base/component/form/input.rs
+++ b/src/base/component/form/input.rs
@@ -8,7 +8,7 @@ pub struct Input {
     input_type  : InputType,
     name        : Option<String>,
     value       : Option<String>,
-    label       : String,
+    label       : Option<String>,
     size        : Option<u16>,
     minlength   : Option<u16>,
     maxlength   : Option<u16>,
@@ -18,7 +18,7 @@ pub struct Input {
     disabled    : Option<String>,
     readonly    : Option<String>,
     required    : Option<String>,
-    help_text   : String,
+    help_text   : Option<String>,
     template    : String,
 }
 
@@ -31,7 +31,7 @@ impl PageComponent for Input {
             input_type  : InputType::Textfield,
             name        : None,
             value       : None,
-            label       : "".to_string(),
+            label       : None,
             size        : Some(60),
             minlength   : None,
             maxlength   : Some(128),
@@ -41,8 +41,8 @@ impl PageComponent for Input {
             disabled    : None,
             readonly    : None,
             required    : None,
-            help_text   : "".to_string(),
-            template    : "default".to_string(),
+            help_text   : None,
+            template    : "default".to_owned(),
         }
     }
 
@@ -75,9 +75,9 @@ impl PageComponent for Input {
         };
         html! {
             div class=(class_item) {
-                @if !self.label.is_empty() {
+                @if self.label != None {
                     label class="form-label" for=[&id_item] {
-                        (self.label) " "
+                        (self.label()) " "
                         @if self.required != None {
                             span
                                 class="form-required"
@@ -103,9 +103,9 @@ impl PageComponent for Input {
                     readonly=[&self.readonly]
                     required=[&self.required]
                     disabled=[&self.disabled];
-                @if !self.help_text.is_empty() {
+                @if self.help_text != None {
                     div class="form-text" {
-                        (self.help_text)
+                        (self.help_text())
                     }
                 }
             }
@@ -167,12 +167,12 @@ impl Input {
     }
 
     pub fn with_value(mut self, value: &str) -> Self {
-        self.value = util::optional_value(value);
+        self.value = util::optional_str(value);
         self
     }
 
     pub fn with_label(mut self, label: &str) -> Self {
-        self.label = label.to_string();
+        self.label = util::optional_str(label);
         self
     }
 
@@ -192,13 +192,13 @@ impl Input {
     }
 
     pub fn with_placeholder(mut self, placeholder: &str) -> Self {
-        self.placeholder = util::optional_value(placeholder);
+        self.placeholder = util::optional_str(placeholder);
         self
     }
 
     pub fn autofocus(mut self, toggle: bool) -> Self {
         self.autofocus = match toggle {
-            true => Some("autofocus".to_string()),
+            true => Some("autofocus".to_owned()),
             false => None
         };
         self
@@ -207,14 +207,14 @@ impl Input {
     pub fn autocomplete(mut self, toggle: bool) -> Self {
         self.autocomplete = match toggle {
             true => None,
-            false => Some("off".to_string())
+            false => Some("off".to_owned())
         };
         self
     }
 
     pub fn disabled(mut self, toggle: bool) -> Self {
         self.disabled = match toggle {
-            true => Some("disabled".to_string()),
+            true => Some("disabled".to_owned()),
             false => None
         };
         self
@@ -222,7 +222,7 @@ impl Input {
 
     pub fn readonly(mut self, toggle: bool) -> Self {
         self.readonly = match toggle {
-            true => Some("readonly".to_string()),
+            true => Some("readonly".to_owned()),
             false => None
         };
         self
@@ -230,34 +230,34 @@ impl Input {
 
     pub fn required(mut self, toggle: bool) -> Self {
         self.required = match toggle {
-            true => Some("required".to_string()),
+            true => Some("required".to_owned()),
             false => None
         };
         self
     }
 
     pub fn with_help_text(mut self, help_text: &str) -> Self {
-        self.help_text = help_text.to_string();
+        self.help_text = util::optional_str(help_text);
         self
     }
 
     pub fn using_template(mut self, template: &str) -> Self {
-        self.template = template.to_string();
+        self.template = template.to_owned();
         self
     }
 
     // Input GETTERS.
 
     pub fn name(&self) -> &str {
-        util::assigned_value(&self.name)
+        util::assigned_str(&self.name)
     }
 
     pub fn value(&self) -> &str {
-        util::assigned_value(&self.value)
+        util::assigned_str(&self.value)
     }
 
     pub fn label(&self) -> &str {
-        self.label.as_str()
+        util::assigned_str(&self.label)
     }
 
     pub fn size(&self) -> Option<u16> {
@@ -273,7 +273,7 @@ impl Input {
     }
 
     pub fn placeholder(&self) -> &str {
-        util::assigned_value(&self.placeholder)
+        util::assigned_str(&self.placeholder)
     }
 
     pub fn has_autofocus(&self) -> bool {
@@ -312,7 +312,7 @@ impl Input {
     }
 
     pub fn help_text(&self) -> &str {
-        self.help_text.as_str()
+        util::assigned_str(&self.help_text)
     }
 
     pub fn template(&self) -> &str {
diff --git a/src/base/component/menu.rs b/src/base/component/menu.rs
index 0f44fad5..d3cdb6b8 100644
--- a/src/base/component/menu.rs
+++ b/src/base/component/menu.rs
@@ -75,7 +75,7 @@ impl MenuItem {
         MenuItem {
             renderable: always,
             weight    : 0,
-            item_type : Some(MenuItemType::Label(label.to_string())),
+            item_type : Some(MenuItemType::Label(label.to_owned())),
         }
     }
 
@@ -84,8 +84,8 @@ impl MenuItem {
             renderable: always,
             weight    : 0,
             item_type : Some(MenuItemType::Link(
-                label.to_string(),
-                path.to_string(),
+                label.to_owned(),
+                path.to_owned(),
             )),
         }
     }
@@ -95,8 +95,8 @@ impl MenuItem {
             renderable: always,
             weight    : 0,
             item_type : Some(MenuItemType::LinkBlank(
-                label.to_string(),
-                path.to_string(),
+                label.to_owned(),
+                path.to_owned(),
             )),
         }
     }
@@ -122,7 +122,7 @@ impl MenuItem {
             renderable: always,
             weight    : 0,
             item_type : Some(MenuItemType::Submenu(
-                label.to_string(),
+                label.to_owned(),
                 menu
             )),
         }
@@ -161,7 +161,7 @@ impl PageComponent for Menu {
             weight    : 0,
             id        : None,
             items     : PageContainer::new(),
-            template  : "default".to_string(),
+            template  : "default".to_owned(),
         }
     }
 
@@ -226,14 +226,14 @@ impl Menu {
     }
 
     pub fn using_template(mut self, template: &str) -> Self {
-        self.template = template.to_string();
+        self.template = template.to_owned();
         self
     }
 
     // Menu GETTERS.
 
     pub fn id(&self) -> &str {
-        util::assigned_value(&self.id)
+        util::assigned_str(&self.id)
     }
 
     pub fn template(&self) -> &str {
diff --git a/src/base/module/admin/mod.rs b/src/base/module/admin/mod.rs
index 5991d4f0..0bb1202d 100644
--- a/src/base/module/admin/mod.rs
+++ b/src/base/module/admin/mod.rs
@@ -15,8 +15,8 @@ impl Module for AdminModule {
         l("module_fullname")
     }
 
-    fn description(&self) -> String {
-        l("module_description")
+    fn description(&self) -> Option<String> {
+        Some(l("module_description"))
     }
 
     fn configure_module(&self, cfg: &mut server::web::ServiceConfig) {
diff --git a/src/base/module/homepage/mod.rs b/src/base/module/homepage/mod.rs
index 386b6716..de4b98ce 100644
--- a/src/base/module/homepage/mod.rs
+++ b/src/base/module/homepage/mod.rs
@@ -13,8 +13,8 @@ impl Module for HomepageModule {
         l("module_fullname")
     }
 
-    fn description(&self) -> String {
-        l("module_description")
+    fn description(&self) -> Option<String> {
+        Some(l("module_description"))
     }
 
     fn configure_module(&self, cfg: &mut server::web::ServiceConfig) {
diff --git a/src/base/module/user/mod.rs b/src/base/module/user/mod.rs
index bbb3ee93..73ab7d16 100644
--- a/src/base/module/user/mod.rs
+++ b/src/base/module/user/mod.rs
@@ -13,8 +13,8 @@ impl Module for UserModule {
         l("module_fullname")
     }
 
-    fn description(&self) -> String {
-        l("module_description")
+    fn description(&self) -> Option<String> {
+        Some(l("module_description"))
     }
 
     fn configure_module(&self, cfg: &mut server::web::ServiceConfig) {
@@ -29,7 +29,7 @@ fn form_login() -> impl PageComponent {
             .with_name("name")
             .with_label(l("username").as_str())
             .with_help_text(t("username_help", &args![
-                "app" => SETTINGS.app.name.to_string()
+                "app" => SETTINGS.app.name.to_owned()
             ]).as_str())
             .autofocus(true)
         )
diff --git a/src/base/theme/aliner/mod.rs b/src/base/theme/aliner/mod.rs
index d27e2f91..b678d4b7 100644
--- a/src/base/theme/aliner/mod.rs
+++ b/src/base/theme/aliner/mod.rs
@@ -10,7 +10,7 @@ impl Theme for AlinerTheme {
     }
 
     fn fullname(&self) -> String {
-        "Aliner".to_string()
+        "Aliner".to_owned()
     }
 
     fn configure_theme(&self, cfg: &mut server::web::ServiceConfig) {
diff --git a/src/base/theme/bootsier/mod.rs b/src/base/theme/bootsier/mod.rs
index 97b7fa46..3a340a84 100644
--- a/src/base/theme/bootsier/mod.rs
+++ b/src/base/theme/bootsier/mod.rs
@@ -12,7 +12,7 @@ impl Theme for BootsierTheme {
     }
 
     fn fullname(&self) -> String {
-        "Bootsier".to_string()
+        "Bootsier".to_owned()
     }
 
     fn configure_theme(&self, cfg: &mut server::web::ServiceConfig) {
diff --git a/src/base/theme/minimal/mod.rs b/src/base/theme/minimal/mod.rs
index 17611468..c6780005 100644
--- a/src/base/theme/minimal/mod.rs
+++ b/src/base/theme/minimal/mod.rs
@@ -8,6 +8,6 @@ impl Theme for MinimalTheme {
     }
 
     fn fullname(&self) -> String {
-        "Minimal".to_string()
+        "Minimal".to_owned()
     }
 }
diff --git a/src/config/settings.rs b/src/config.rs
similarity index 97%
rename from src/config/settings.rs
rename to src/config.rs
index 66ddbe42..bd80bd76 100644
--- a/src/config/settings.rs
+++ b/src/config.rs
@@ -1,11 +1,13 @@
 use crate::Lazy;
-use crate::config::CONFIG_DIR;
 
 use config_rs::{Config, File};
 use serde::Deserialize;
 
 use std::env;
 
+/// Nombre del directorio donde se encuentra la configuración.
+const CONFIG_DIR: &'static str = "config";
+
 /// Al arrancar la aplicación, carga los valores originales "clave = valor" de
 /// los archivos de configuración. Con [`config_map`] se asignarán los ajustes
 /// globales ([`SETTINGS`]); y se podrán asignar los ajustes específicos de la
diff --git a/src/config/mod.rs b/src/config/mod.rs
deleted file mode 100644
index aba410ee..00000000
--- a/src/config/mod.rs
+++ /dev/null
@@ -1,5 +0,0 @@
-/// Nombre del directorio donde se encuentra la configuración.
-pub const CONFIG_DIR: &'static str = "config";
-
-mod settings;
-pub use settings::{CONFIG, SETTINGS};
diff --git a/src/core/all.rs b/src/core/global.rs
similarity index 83%
rename from src/core/all.rs
rename to src/core/global.rs
index eb7bed10..1d64d44f 100644
--- a/src/core/all.rs
+++ b/src/core/global.rs
@@ -3,7 +3,6 @@ use crate::core::theme::Theme;
 use crate::core::module::Module;
 use crate::core::response::page::PageContainer;
 use crate::core::server;
-use crate::base;
 
 use std::sync::RwLock;
 use std::collections::HashMap;
@@ -15,11 +14,7 @@ include!(concat!(env!("OUT_DIR"), "/theme.rs"));
 // -----------------------------------------------------------------------------
 
 pub static THEMES: Lazy<RwLock<Vec<&dyn Theme>>> = Lazy::new(|| {
-    RwLock::new(vec![
-        &base::theme::aliner::AlinerTheme,
-        &base::theme::minimal::MinimalTheme,
-        &base::theme::bootsier::BootsierTheme,
-    ])
+    RwLock::new(Vec::new())
 });
 
 pub fn themes(cfg: &mut server::web::ServiceConfig) {
@@ -38,10 +33,7 @@ pub fn themes(cfg: &mut server::web::ServiceConfig) {
 // -----------------------------------------------------------------------------
 
 pub static MODULES: Lazy<RwLock<Vec<&dyn Module>>> = Lazy::new(|| {
-    RwLock::new(vec![
-        &base::module::admin::AdminModule,
-        &base::module::user::UserModule,
-    ])
+    RwLock::new(Vec::new())
 });
 
 pub fn modules(cfg: &mut server::web::ServiceConfig) {
diff --git a/src/core/mod.rs b/src/core/mod.rs
index 40530f15..26618959 100644
--- a/src/core/mod.rs
+++ b/src/core/mod.rs
@@ -1,6 +1,6 @@
 pub use actix_web::dev::Server;
 
-mod all;
+mod global;
 
 pub mod theme;
 pub mod module;
diff --git a/src/core/module/api.rs b/src/core/module/api.rs
deleted file mode 100644
index 83be71c3..00000000
--- a/src/core/module/api.rs
+++ /dev/null
@@ -1,28 +0,0 @@
-use crate::core::{all, server};
-
-/// Los módulos deben implementar este *trait*.
-pub trait Module: Send + Sync {
-    fn name(&self) -> &'static str;
-
-    fn fullname(&self) -> String;
-
-    fn description(&self) -> String {
-        "".to_string()
-    }
-
-    #[allow(unused_variables)]
-    fn configure_module(&self, cfg: &mut server::web::ServiceConfig) {
-    }
-}
-
-pub fn register_module(m: &'static (dyn Module + 'static)) {
-    all::MODULES.write().unwrap().push(m);
-}
-
-pub fn find_module(name: &str) -> Option<&'static (dyn Module + 'static)> {
-    let modules = all::MODULES.write().unwrap();
-    match modules.iter().find(|t| t.name() == name) {
-        Some(module) => Some(*module),
-        _ => None,
-    }
-}
diff --git a/src/core/module/definition.rs b/src/core/module/definition.rs
new file mode 100644
index 00000000..40e9cee8
--- /dev/null
+++ b/src/core/module/definition.rs
@@ -0,0 +1,16 @@
+use crate::core::server;
+
+/// Los módulos deben implementar este *trait*.
+pub trait Module: Send + Sync {
+    fn name(&self) -> &'static str;
+
+    fn fullname(&self) -> String;
+
+    fn description(&self) -> Option<String> {
+        None
+    }
+
+    #[allow(unused_variables)]
+    fn configure_module(&self, cfg: &mut server::web::ServiceConfig) {
+    }
+}
diff --git a/src/core/module/mod.rs b/src/core/module/mod.rs
index 08686bcd..439cff79 100644
--- a/src/core/module/mod.rs
+++ b/src/core/module/mod.rs
@@ -1,2 +1,16 @@
-mod api;
-pub use api::{Module, find_module, register_module};
+use crate::core::global;
+
+mod definition;
+pub use definition::Module;
+
+pub fn register_module(m: &'static (dyn Module + 'static)) {
+    global::MODULES.write().unwrap().push(m);
+}
+
+pub fn find_module(name: &str) -> Option<&'static (dyn Module + 'static)> {
+    let modules = global::MODULES.write().unwrap();
+    match modules.iter().find(|t| t.name() == name) {
+        Some(module) => Some(*module),
+        _ => None,
+    }
+}
diff --git a/src/core/response/page/assets.rs b/src/core/response/page/assets.rs
index 77174e58..11cdd35c 100644
--- a/src/core/response/page/assets.rs
+++ b/src/core/response/page/assets.rs
@@ -1,10 +1,10 @@
 use crate::{Lazy, base};
 use crate::config::SETTINGS;
-use crate::core::all;
+use crate::core::global;
 use crate::core::theme::{Markup, PreEscaped, Theme, find_theme, html};
 
 static DEFAULT_THEME: Lazy<&dyn Theme> = Lazy::new(|| {
-    for t in all::THEMES.read().unwrap().iter() {
+    for t in global::THEMES.read().unwrap().iter() {
         if t.name().to_lowercase() == SETTINGS.app.theme.to_lowercase() {
             return *t;
         }
@@ -73,7 +73,7 @@ impl Favicon {
     ) -> Self {
         let mut link: String = format!("<link rel=\"{}\"", rel);
         if let Some(i) = source.rfind('.') {
-            link = match source[i..].to_string().to_lowercase().as_str() {
+            link = match source[i..].to_owned().to_lowercase().as_str() {
                 ".gif" => format!("{} type=\"image/gif\"", link),
                 ".ico" => format!("{} type=\"image/x-icon\"", link),
                 ".jpg" => format!("{} type=\"image/jpg\"", link),
@@ -295,14 +295,14 @@ impl PageAssets {
         if id.is_empty() {
             let prefix = prefix.trim().replace(" ", "_").to_lowercase();
             let prefix = if prefix.is_empty() {
-                "prefix".to_string()
+                "prefix".to_owned()
             } else {
                 prefix
             };
             self.id_counter += 1;
             [prefix, self.id_counter.to_string()].join("-")
         } else {
-            id.to_string()
+            id.to_owned()
         }
     }
 }
diff --git a/src/core/response/page/component.rs b/src/core/response/page/component.rs
index ccc0facb..1472ffe2 100644
--- a/src/core/response/page/component.rs
+++ b/src/core/response/page/component.rs
@@ -18,11 +18,11 @@ pub trait PageComponent: Downcast + Send + Sync {
     }
 
     fn fullname(&self) -> String {
-        type_name::<Self>().to_string()
+        type_name::<Self>().to_owned()
     }
 
-    fn description(&self) -> String {
-        "".to_string()
+    fn description(&self) -> Option<String> {
+        None
     }
 
     fn is_renderable(&self) -> bool {
diff --git a/src/core/response/page/page.rs b/src/core/response/page/page.rs
index 18e8c917..8052683d 100644
--- a/src/core/response/page/page.rs
+++ b/src/core/response/page/page.rs
@@ -1,6 +1,6 @@
 use crate::{Lazy, trace, util};
 use crate::config::SETTINGS;
-use crate::core::{all, server};
+use crate::core::{global, server};
 use crate::core::theme::{DOCTYPE, Markup, html};
 use crate::core::response::page::{PageAssets, PageComponent, PageContainer};
 
@@ -19,9 +19,9 @@ static DEFAULT_LANGUAGE: Lazy<Option<String>> = Lazy::new(|| {
 static DEFAULT_DIRECTION: Lazy<Option<String>> = Lazy::new(|| {
     let direction = SETTINGS.app.direction.to_lowercase();
     match direction.as_str() {
-        "auto" => Some("auto".to_string()),
-        "ltr" => Some("ltr".to_string()),
-        "rtl" => Some("rtl".to_string()),
+        "auto" => Some("auto".to_owned()),
+        "ltr" => Some("ltr".to_owned()),
+        "rtl" => Some("rtl".to_owned()),
         "" => None,
         _ => {
             trace::warn!(
@@ -44,7 +44,7 @@ pub struct Page<'a> {
     assets      : PageAssets,
     body_classes: Cow<'a, str>,
     regions     : HashMap<&'a str, PageContainer>,
-    template    : Option<String>,
+    template    : String,
 }
 
 impl<'a> Page<'a> {
@@ -52,45 +52,45 @@ impl<'a> Page<'a> {
     pub fn prepare() -> Self {
         Page {
             language    : match &*DEFAULT_LANGUAGE {
-                Some(language) => Some(language.to_string()),
+                Some(language) => Some(language.to_owned()),
                 _ => None,
             },
             direction   : match &*DEFAULT_DIRECTION {
-                Some(direction) => Some(direction.to_string()),
+                Some(direction) => Some(direction.to_owned()),
                 _ => None,
             },
             title       : None,
             description : None,
             body_classes: "body".into(),
             assets      : PageAssets::new(),
-            regions     : all::COMPONENTS.read().unwrap().clone(),
-            template    : Some("default".to_string()),
+            regions     : global::COMPONENTS.read().unwrap().clone(),
+            template    : "default".to_owned(),
         }
     }
 
     // Page BUILDER.
 
     pub fn with_language(&mut self, language: &str) -> &mut Self {
-        self.language = util::optional_value(language);
+        self.language = util::optional_str(language);
         self
     }
 
     pub fn with_direction(&mut self, dir: TextDirection) -> &mut Self {
         self.direction = match dir {
-            TextDirection::Auto => Some("auto".to_string()),
-            TextDirection::LeftToRight => Some("ltr".to_string()),
-            TextDirection::RightToLeft => Some("rtl".to_string()),
+            TextDirection::Auto => Some("auto".to_owned()),
+            TextDirection::LeftToRight => Some("ltr".to_owned()),
+            TextDirection::RightToLeft => Some("rtl".to_owned()),
         };
         self
     }
 
     pub fn with_title(&mut self, title: &str) -> &mut Self {
-        self.title = util::optional_value(title);
+        self.title = util::optional_str(title);
         self
     }
 
     pub fn with_description(&mut self, description: &str) -> &mut Self {
-        self.description = util::optional_value(description);
+        self.description = util::optional_str(description);
         self
     }
 
@@ -120,26 +120,26 @@ impl<'a> Page<'a> {
     }
 
     pub fn using_template(&mut self, template: &str) -> &mut Self {
-        self.template = util::optional_value(template);
+        self.template = template.to_owned();
         self
     }
 
     // Page GETTERS.
 
     pub fn language(&self) -> &str {
-        util::assigned_value(&self.language)
+        util::assigned_str(&self.language)
     }
 
     pub fn direction(&self) -> &str {
-        util::assigned_value(&self.direction)
+        util::assigned_str(&self.direction)
     }
 
     pub fn title(&self) -> &str {
-        util::assigned_value(&self.title)
+        util::assigned_str(&self.title)
     }
 
     pub fn description(&self) -> &str {
-        util::assigned_value(&self.description)
+        util::assigned_str(&self.description)
     }
 
     pub fn body_classes(&self) -> &str {
@@ -154,7 +154,7 @@ impl<'a> Page<'a> {
     }
 
     pub fn template(&self) -> &str {
-        util::assigned_value(&self.template)
+        self.template.as_str()
     }
 
     // Page RENDER.
@@ -208,7 +208,7 @@ pub fn render_component(
 }
 
 pub fn add_component_to(region: &'static str, component: impl PageComponent) {
-    let mut hmap = all::COMPONENTS.write().unwrap();
+    let mut hmap = global::COMPONENTS.write().unwrap();
     if let Some(regions) = hmap.get_mut(region) {
         regions.add(component);
     } else {
diff --git a/src/core/server/langid.rs b/src/core/server/langid.rs
deleted file mode 100644
index 3638a6a4..00000000
--- a/src/core/server/langid.rs
+++ /dev/null
@@ -1,23 +0,0 @@
-use crate::{Lazy, trace};
-use crate::config::SETTINGS;
-
-use unic_langid::LanguageIdentifier;
-
-/// Almacena el Identificador de Idioma Unicode ([Unicode Language Identifier]
-/// (https://unicode.org/reports/tr35/tr35.html#Unicode_language_identifier)) de
-/// la aplicación, obtenido de `SETTINGS.app.language`.
-pub static LANGID: Lazy<LanguageIdentifier> = Lazy::new(|| {
-    match SETTINGS.app.language.parse() {
-        Ok(language) => language,
-        Err(_) => {
-            trace::warn!(
-                "Failed to parse language \"{}\". {}. {}. {}.",
-                SETTINGS.app.language,
-                "Unicode Language Identifier not recognized",
-                "Using \"en-US\"",
-                "Check the settings file",
-            );
-            "en-US".parse().unwrap()
-        }
-    }
-});
diff --git a/src/core/server/main.rs b/src/core/server/main.rs
index c39c9f83..b6800142 100644
--- a/src/core/server/main.rs
+++ b/src/core/server/main.rs
@@ -1,6 +1,7 @@
-use crate::{Lazy, base, trace};
+use crate::{Lazy, base, locale, trace};
 use crate::config::SETTINGS;
-use crate::core::{Server, all, server};
+use crate::core::{Server, global, server};
+use crate::core::theme::register_theme;
 use crate::core::module::register_module;
 
 use actix_web::middleware::normalize;
@@ -32,11 +33,20 @@ pub fn run(bootstrap: Option<fn()>) -> Result<Server, std::io::Error> {
         );
     }
 
-    // Inicia la traza de la aplicación.
+    // Inicia registro de trazas y eventos.
     Lazy::force(&server::tracing::TRACING);
 
     // Asigna identificador de idioma.
-    Lazy::force(&server::langid::LANGID);
+    Lazy::force(&locale::LANGID);
+
+    // Registra los temas predefinidos.
+    register_theme(&base::theme::aliner::AlinerTheme);
+    register_theme(&base::theme::minimal::MinimalTheme);
+    register_theme(&base::theme::bootsier::BootsierTheme);
+
+    // Registra los módulos predeterminados.
+    register_module(&base::module::admin::AdminModule);
+    register_module(&base::module::user::UserModule);
 
     // Ejecuta la función de inicio de la aplicación.
     if bootstrap != None {
@@ -54,8 +64,8 @@ pub fn run(bootstrap: Option<fn()>) -> Result<Server, std::io::Error> {
         server::App::new()
             .wrap(tracing_actix_web::TracingLogger)
             .wrap(normalize::NormalizePath::new(normalize::TrailingSlash::Trim))
-            .configure(&all::themes)
-            .configure(&all::modules)
+            .configure(&global::themes)
+            .configure(&global::modules)
         })
         .bind(format!("{}:{}",
             &SETTINGS.webserver.bind_address,
diff --git a/src/core/server/mod.rs b/src/core/server/mod.rs
index 6bb25129..7db53759 100644
--- a/src/core/server/mod.rs
+++ b/src/core/server/mod.rs
@@ -4,8 +4,5 @@ pub use actix_web::{
 
 mod tracing;
 
-mod langid;
-pub use langid::LANGID;
-
 mod main;
 pub use main::run;
diff --git a/src/core/server/tracing.rs b/src/core/server/tracing.rs
index fd907461..a9804213 100644
--- a/src/core/server/tracing.rs
+++ b/src/core/server/tracing.rs
@@ -4,6 +4,19 @@ use crate::config::SETTINGS;
 use tracing_appender::non_blocking::WorkerGuard;
 use tracing_subscriber::EnvFilter;
 
+/// Registro de trazas y eventos de la aplicación.
+///
+/// Para aumentar el rendimiento, un subproceso dedicado utiliza un sistema de
+/// escritura sin bloqueo (*non-blocking writer*) que actúa periódicamente en
+/// vez de enviar cada traza o evento al instante. Si el programa termina
+/// abruptamente (por ejemplo, por un `panic!` o un `std::process::exit`), es
+/// posible que algunas trazas o eventos no se envíen.
+///
+/// Puesto que las trazas o eventos registrados poco antes de la caída de una
+/// aplicación suelen ser importantes para diagnosticar la causa del fallo, con
+/// `Lazy<WorkerGuard>` se garantiza que todos los registros almacenados se
+/// enviarán antes de terminar la ejecución.
+
 pub static TRACING: Lazy<WorkerGuard> = Lazy::new(|| {
     let env_filter = EnvFilter::try_new(&SETTINGS.log.tracing)
         .unwrap_or(EnvFilter::new("Info"));
diff --git a/src/core/theme/api.rs b/src/core/theme/definition.rs
similarity index 85%
rename from src/core/theme/api.rs
rename to src/core/theme/definition.rs
index efbc9cef..12d9e05f 100644
--- a/src/core/theme/api.rs
+++ b/src/core/theme/definition.rs
@@ -1,5 +1,5 @@
 use crate::config::SETTINGS;
-use crate::core::{all, server};
+use crate::core::server;
 use crate::core::theme::{Markup, html};
 use crate::core::response::page::{Page, PageAssets, PageComponent};
 use crate::base::component::Chunck;
@@ -10,8 +10,8 @@ pub trait Theme: Send + Sync {
 
     fn fullname(&self) -> String;
 
-    fn description(&self) -> String {
-        "".to_string()
+    fn description(&self) -> Option<String> {
+        None
     }
 
     #[allow(unused_variables)]
@@ -25,7 +25,7 @@ pub trait Theme: Send + Sync {
     fn render_page_head(&self, page: &mut Page) -> Markup {
         let title = page.title();
         let title = if title.is_empty() {
-            SETTINGS.app.name.to_string()
+            SETTINGS.app.name.to_owned()
         } else {
             [SETTINGS.app.name.to_string(), title.to_string()].join(" | ")
         };
@@ -104,15 +104,3 @@ pub trait Theme: Send + Sync {
             .render()
     }
 }
-
-pub fn register_theme(t: &'static (dyn Theme + 'static)) {
-    all::THEMES.write().unwrap().push(t);
-}
-
-pub fn find_theme(name: &str) -> Option<&'static (dyn Theme + 'static)> {
-    let themes = all::THEMES.write().unwrap();
-    match themes.iter().find(|t| t.name() == name) {
-        Some(theme) => Some(*theme),
-        _ => None,
-    }
-}
diff --git a/src/core/theme/mod.rs b/src/core/theme/mod.rs
index 9f708803..8292ade6 100644
--- a/src/core/theme/mod.rs
+++ b/src/core/theme/mod.rs
@@ -1,4 +1,18 @@
+use crate::core::global;
+
 pub use maud::{DOCTYPE, Markup, PreEscaped, html};
 
-mod api;
-pub use api::{Theme, find_theme, register_theme};
+mod definition;
+pub use definition::Theme;
+
+pub fn register_theme(t: &'static (dyn Theme + 'static)) {
+    global::THEMES.write().unwrap().push(t);
+}
+
+pub fn find_theme(name: &str) -> Option<&'static (dyn Theme + 'static)> {
+    let themes = global::THEMES.write().unwrap();
+    match themes.iter().find(|t| t.name() == name) {
+        Some(theme) => Some(*theme),
+        _ => None,
+    }
+}
diff --git a/src/lib.rs b/src/lib.rs
index 42f51a3a..7d17db44 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -8,7 +8,7 @@ pub use once_cell::sync::Lazy;
 // -----------------------------------------------------------------------------
 
 pub mod config;     // Gestión de la configuración.
-pub mod trace;      // Traza de ejecución.
+pub mod trace;      // Registro de trazas y eventos de la aplicación.
 pub mod locale;     // Localización.
 pub mod core;       // Servidor web y sistemas para Temas, Módulos y Respuestas.
 pub mod base;       // Temas, Módulos y Componentes base.
diff --git a/src/locale.rs b/src/locale.rs
index b43d9fd6..e3639858 100644
--- a/src/locale.rs
+++ b/src/locale.rs
@@ -2,12 +2,35 @@ pub use fluent_templates::{static_loader as static_locale, Loader as Locale};
 pub use fluent_templates;
 pub use fluent_templates::fluent_bundle::FluentValue;
 
+use crate::{Lazy, trace};
+use crate::config::SETTINGS;
+
+use unic_langid::LanguageIdentifier;
+
+/// Almacena el Identificador de Idioma Unicode ([Unicode Language Identifier]
+/// (https://unicode.org/reports/tr35/tr35.html#Unicode_language_identifier)) de
+/// la aplicación, obtenido de `SETTINGS.app.language`.
+pub static LANGID: Lazy<LanguageIdentifier> = Lazy::new(|| {
+    match SETTINGS.app.language.parse() {
+        Ok(language) => language,
+        Err(_) => {
+            trace::warn!(
+                "Failed to parse language \"{}\". {}. {}. {}.",
+                SETTINGS.app.language,
+                "Unicode Language Identifier not recognized",
+                "Using \"en-US\"",
+                "Check the settings file",
+            );
+            "en-US".parse().unwrap()
+        }
+    }
+});
+
 #[macro_export]
 /// Permite integrar fácilmente localización en temas, módulos y componentes.
 macro_rules! localize {
     ( $DEF_LANGID:literal, $locales:literal $(, $core_locales:literal)? ) => {
         use $crate::locale::*;
-        use $crate::core::server::LANGID;
 
         static_locale! {
             static LOCALES = {
diff --git a/src/util.rs b/src/util.rs
index 638e948f..3fff0a23 100644
--- a/src/util.rs
+++ b/src/util.rs
@@ -26,17 +26,17 @@ pub fn valid_id(id: &str) -> Option<String> {
     }
 }
 
-pub fn optional_value(value: &str) -> Option<String> {
-    let value = value.to_string();
-    match value.is_empty() {
+pub fn optional_str(s: &str) -> Option<String> {
+    let s = s.to_owned();
+    match s.is_empty() {
         true => None,
-        false => Some(value),
+        false => Some(s),
     }
 }
 
-pub fn assigned_value(value: &Option<String>) -> &str {
-    match value {
-        Some(value) => value.as_str(),
+pub fn assigned_str(optional: &Option<String>) -> &str {
+    match optional {
+        Some(o) => o.as_str(),
         _ => "",
     }
 }