diff --git a/Admin/Install/db.json b/Admin/Install/db.json
index 39f6fd8..2a1d8cc 100755
--- a/Admin/Install/db.json
+++ b/Admin/Install/db.json
@@ -41,7 +41,7 @@
             "billing_type_is_template": {
                 "description": "What kind of bill is it?",
                 "name": "billing_type_is_template",
-                "type": "TINYINT",
+                "type": "TINYINT(1)",
                 "null": false
             }
         }
@@ -659,7 +659,7 @@
             },
             "billing_bill_subscription_account": {
                 "name": "billing_bill_subscription_account",
-                "type": "TINYINT(1)",
+                "type": "INT",
                 "null": true,
                 "default": null,
                 "foreignTable": "account",
diff --git a/Controller/ApiController.php b/Controller/ApiController.php
index 2a4b676..fedf72f 100755
--- a/Controller/ApiController.php
+++ b/Controller/ApiController.php
@@ -37,6 +37,7 @@ use Modules\Media\Models\UploadStatus;
 use Modules\SupplierManagement\Models\NullSupplier;
 use Modules\SupplierManagement\Models\SupplierMapper;
 use phpOMS\Autoloader;
+use phpOMS\Localization\BaseStringL11n;
 use phpOMS\Localization\ISO639x1Enum;
 use phpOMS\Localization\Money;
 use phpOMS\Message\Http\HttpRequest;
diff --git a/Models/Bill.php b/Models/Bill.php
index 407496b..f9ab7da 100755
--- a/Models/Bill.php
+++ b/Models/Bill.php
@@ -622,13 +622,13 @@ class Bill implements \JsonSerializable
     /**
      * Add Bill element.
      *
-     * @param mixed $element Bill element
+     * @param BillElement $element Bill element
      *
      * @return void
      *
      * @since 1.0.0
      */
-    public function addElement($element) : void
+    public function addElement(BillElement $element) : void
     {
         $this->elements[] = $element;
     }
@@ -713,13 +713,13 @@ class Bill implements \JsonSerializable
     /**
      * Get media file by type
      *
-     * @param null|int $type Media type
+     * @param int $type Media type
      *
      * @return Media
      *
      * @since 1.0.0
      */
-    public function getFileByType(int $type = null) : Media
+    public function getFileByType(int $type) : Media
     {
         foreach ($this->media as $file) {
             if ($file->type->getId() === $type) {
diff --git a/Models/BillElementMapper.php b/Models/BillElementMapper.php
index 4c0d420..9b6eb3a 100755
--- a/Models/BillElementMapper.php
+++ b/Models/BillElementMapper.php
@@ -66,7 +66,7 @@ final class BillElementMapper extends DataMapperFactory
     /**
      * Belongs to.
      *
-     * @var array<string, array{mapper:string, external:string, column?:string, by?:string}>
+     * @var array<string, array{mapper:class-string, external:string, column?:string, by?:string}>
      * @since 1.0.0
      */
     public const BELONGS_TO = [
diff --git a/Models/BillMapper.php b/Models/BillMapper.php
index 043b2e1..a241f87 100755
--- a/Models/BillMapper.php
+++ b/Models/BillMapper.php
@@ -86,7 +86,7 @@ class BillMapper extends DataMapperFactory
     /**
      * Has many relation.
      *
-     * @var array<string, array{mapper:string, table:string, self?:?string, external?:?string, column?:string}>
+     * @var array<string, array{mapper:class-string, table:string, self?:?string, external?:?string, column?:string}>
      * @since 1.0.0
      */
     public const HAS_MANY = [
@@ -113,7 +113,7 @@ class BillMapper extends DataMapperFactory
     /**
      * Has one relation.
      *
-     * @var array<string, array{mapper:string, external:string, by?:string, column?:string, conditional?:bool}>
+     * @var array<string, array{mapper:class-string, external:string, by?:string, column?:string, conditional?:bool}>
      * @since 1.0.0
      */
     public const OWNS_ONE = [
@@ -130,7 +130,7 @@ class BillMapper extends DataMapperFactory
     /**
      * Belongs to.
      *
-     * @var array<string, array{mapper:string, external:string, column?:string, by?:string}>
+     * @var array<string, array{mapper:class-string, external:string, column?:string, by?:string}>
      * @since 1.0.0
      */
     public const BELONGS_TO = [
diff --git a/Models/BillType.php b/Models/BillType.php
index 12daebf..c295115 100755
--- a/Models/BillType.php
+++ b/Models/BillType.php
@@ -54,6 +54,8 @@ class BillType implements \JsonSerializable
      */
     protected string | BaseStringL11n $l11n;
 
+    public bool $isTemplate = false;
+
     /**
      * Constructor.
      *
@@ -94,7 +96,8 @@ class BillType implements \JsonSerializable
         if ($l11n instanceof BaseStringL11n) {
             $this->l11n = $l11n;
         } elseif (isset($this->l11n) && $this->l11n instanceof BaseStringL11n) {
-            $this->l11n->content = $l11n;
+            $this->l11n->content  = $l11n;
+            $this->l11n->setLanguage($lang);
         } else {
             $this->l11n          = new BaseStringL11n();
             $this->l11n->content = $l11n;
@@ -110,6 +113,10 @@ class BillType implements \JsonSerializable
      */
     public function getL11n() : string
     {
+        if (!isset($this->l11n)) {
+            return '';
+        }
+
         return $this->l11n instanceof BaseStringL11n ? $this->l11n->content : $this->l11n;
     }
 
diff --git a/Models/BillTypeL11nMapper.php b/Models/BillTypeL11nMapper.php
index ac4bf90..be7f67b 100755
--- a/Models/BillTypeL11nMapper.php
+++ b/Models/BillTypeL11nMapper.php
@@ -59,7 +59,7 @@ final class BillTypeL11nMapper extends DataMapperFactory
     /**
      * Model to use by the mapper.
      *
-     * @var string
+     * @var class-string
      * @since 1.0.0
      */
     public const MODEL = BaseStringL11n::class;
diff --git a/Models/BillTypeMapper.php b/Models/BillTypeMapper.php
index 3aa8d0c..c907924 100755
--- a/Models/BillTypeMapper.php
+++ b/Models/BillTypeMapper.php
@@ -40,12 +40,13 @@ final class BillTypeMapper extends DataMapperFactory
         'billing_type_template'            => ['name' => 'billing_type_template',       'type' => 'int',    'internal' => 'template'],
         'billing_type_transfer_type'       => ['name' => 'billing_type_transfer_type',  'type' => 'int',    'internal' => 'transferType'],
         'billing_type_transfer_stock'      => ['name' => 'billing_type_transfer_stock', 'type' => 'bool',   'internal' => 'transferStock'],
+        'billing_type_is_template'      => ['name' => 'billing_type_is_template', 'type' => 'bool',   'internal' => 'isTemplate'],
     ];
 
     /**
      * Belongs to.
      *
-     * @var array<string, array{mapper:string, external:string, by?:string, column?:string, conditional?:bool}>
+     * @var array<string, array{mapper:class-string, external:string, by?:string, column?:string, conditional?:bool}>
      * @since 1.0.0
      */
     public const OWNS_ONE = [
@@ -58,7 +59,7 @@ final class BillTypeMapper extends DataMapperFactory
     /**
      * Has many relation.
      *
-     * @var array<string, array{mapper:string, table:string, self?:?string, external?:?string, column?:string}>
+     * @var array<string, array{mapper:class-string, table:string, self?:?string, external?:?string, column?:string}>
      * @since 1.0.0
      */
     public const HAS_MANY = [
@@ -74,7 +75,7 @@ final class BillTypeMapper extends DataMapperFactory
     /**
      * Belongs to.
      *
-     * @var array<string, array{mapper:string, self:string}>
+     * @var array<string, array{mapper:class-string, self:string}>
      * @since 1.0.0
      */
     /*
@@ -89,7 +90,7 @@ final class BillTypeMapper extends DataMapperFactory
     /**
      * Model to use by the mapper.
      *
-     * @var string
+     * @var class-string
      * @since 1.0.0
      */
     public const MODEL = BillType::class;
diff --git a/Models/PurchaseBillMapper.php b/Models/PurchaseBillMapper.php
index 433e095..7f6d6c2 100755
--- a/Models/PurchaseBillMapper.php
+++ b/Models/PurchaseBillMapper.php
@@ -32,7 +32,7 @@ final class PurchaseBillMapper extends BillMapper
     /**
      * Model to use by the mapper.
      *
-     * @var string
+     * @var class-string
      * @since 1.0.0
      */
     public const MODEL = Bill::class;
diff --git a/Models/SalesBillMapper.php b/Models/SalesBillMapper.php
index 80f3e66..1422226 100755
--- a/Models/SalesBillMapper.php
+++ b/Models/SalesBillMapper.php
@@ -32,7 +32,7 @@ final class SalesBillMapper extends BillMapper
     /**
      * Model to use by the mapper.
      *
-     * @var string
+     * @var class-string
      * @since 1.0.0
      */
     public const MODEL = Bill::class;
diff --git a/Models/StockBillMapper.php b/Models/StockBillMapper.php
index 934c5f1..7a74349 100755
--- a/Models/StockBillMapper.php
+++ b/Models/StockBillMapper.php
@@ -29,7 +29,7 @@ final class StockBillMapper extends BillMapper
     /**
      * Model to use by the mapper.
      *
-     * @var string
+     * @var class-string
      * @since 1.0.0
      */
     public const MODEL = Bill::class;
diff --git a/info.json b/info.json
index 63015f3..006de7b 100755
--- a/info.json
+++ b/info.json
@@ -20,6 +20,7 @@
         "Admin": "1.0.0",
         "Sales": "1.0.0",
         "Media": "1.0.0",
+        "Calendar": "1.0.0",
         "ItemManagement": "1.0.0",
         "ClientManagement": "1.0.0",
         "SupplierManagement": "1.0.0"