diff --git a/files/constants.php b/files/constants.php
index a6fb0587..0a7a5c5d 100644
--- a/files/constants.php
+++ b/files/constants.php
@@ -98,9 +98,6 @@
 const PHPFHIR_TRAIT_SOURCE_XMLNS = 'SourceXMLNamespaceTrait';
 
 // Core enums
-const PHPFHIR_ENUM_FACTORY_VERSION_CONFIG_KEY = 'FactoryVersionConfigKey';
-const PHPFHIR_ENUM_FACTORY_CONFIG_KEY = 'FactoryConfigKeyEnum';
-const PHPFHIR_ENUM_VERSION_CONFIG_KEY = 'VersionConfigKeyEnum';
 const PHPFHIR_ENUM_VERSION = 'VersionEnum';
 
 // Core exceptions
@@ -111,12 +108,10 @@
 // Core encoding entities
 const PHPFHIR_ENCODING_CLASSNAME_XML_WRITER = 'XMLWriter';
 const PHPFHIR_ENCODING_ENUM_XML_LOCATION = 'XMLLocationEnum';
-const PHPFHIR_ENCODING_ENUM_SERIALIZE_CONFIG_KEY = 'SerializeConfigKeyEnum';
+const PHPFHIR_ENCODING_TRAIT_XML_LOCATION = 'XMLLocationTrait';
 const PHPFHIR_ENCODING_CLASSNAME_SERIALIZE_CONFIG = 'SerializeConfig';
-const PHPFHIR_ENCODING_ENUM_UNSERIALIZE_CONFIG_KEY = 'UnserializeConfigKeyEnum';
 const PHPFHIR_ENCODING_CLASSNAME_UNSERIALIZE_CONFIG = 'UnserializeConfig';
 
-
 // Core client entities
 const PHPFHIR_CLIENT_INTERFACE_CLIENT = 'ClientInterface';
 const PHPFHIR_CLIENT_CLASSNAME_CLIENT = 'Client';
diff --git a/src/Utilities/ImportUtils.php b/src/Utilities/ImportUtils.php
index 83ce7655..32a00287 100644
--- a/src/Utilities/ImportUtils.php
+++ b/src/Utilities/ImportUtils.php
@@ -50,7 +50,6 @@ public static function buildVersionTypeImports(Type $type): void
         if (!$type->isAbstract()) {
             $imports->addCoreFileImportsByName(
                 PHPFHIR_ENCODING_CLASSNAME_XML_WRITER,
-                PHPFHIR_ENCODING_ENUM_XML_LOCATION,
             );
         }
 
@@ -98,6 +97,16 @@ public static function buildVersionTypeImports(Type $type): void
             );
         }
 
+        if ($type->isValueContainer()
+            || $type->hasValueContainerParent()
+            || $type->hasPrimitiveContainerParent()
+            || $typeKind->isOneOf(TypeKindEnum::PRIMITIVE, TypeKindEnum::LIST, TypeKindEnum::PRIMITIVE_CONTAINER)) {
+            $imports->addCoreFileImportsByName(PHPFHIR_ENCODING_ENUM_XML_LOCATION);
+            if (!$type->hasValueContainerParent() && !$type->hasPrimitiveContainerParent()) {
+                $imports->addCoreFileImportsByName(PHPFHIR_ENCODING_TRAIT_XML_LOCATION);
+            }
+        }
+
         if ($restrictionBaseType = $type->getRestrictionBaseFHIRType()) {
             $imports->addImport(
                 $restrictionBaseType->getFullyQualifiedNamespace(false),
diff --git a/src/Utilities/TypeHintUtils.php b/src/Utilities/TypeHintUtils.php
index 9210ff3b..54a605ea 100644
--- a/src/Utilities/TypeHintUtils.php
+++ b/src/Utilities/TypeHintUtils.php
@@ -38,9 +38,11 @@ public static function primitivePHPValueTypeHint(Version           $version,
                                                      bool              $nullable,
                                                      bool              $stringable = false): string
     {
-        return ($nullable ? 'null|' : '')
-            . ($stringable ? 'string|' : '')
-            . $primitiveType->getPHPReturnValueTypeHint();
+        $base = $primitiveType->getPHPReturnValueTypeHint();
+        if ($stringable && !str_contains($base, 'string')) {
+            $base = "string|{$base}";
+        }
+        return $nullable ? "null|{$base}" : $base;
     }
 
     /**
@@ -349,6 +351,6 @@ public static function buildSetterParameterHint(Version  $version,
             array_unshift($hintTypes, 'null');
         }
 
-        return implode('|', $hintTypes);
+        return implode('|', array_unique($hintTypes));
     }
 }
\ No newline at end of file
diff --git a/src/Version/Definition/Type.php b/src/Version/Definition/Type.php
index 45d2cadb..7ae155ee 100644
--- a/src/Version/Definition/Type.php
+++ b/src/Version/Definition/Type.php
@@ -380,11 +380,9 @@ public function hasPropertiesWithValidations(): bool
     public function getAllPropertiesIndexedIterator(): iterable
     {
         $p = [];
-        foreach ($this->getParentTypes() as $parentType) {
+        foreach ($this->getRootFirstParentTypes() as $parentType) {
             foreach ($parentType->getProperties()->getGenerator() as $property) {
-                if (!isset($p[$property->getName()])) {
-                    $p[$property->getName()] = $property;
-                }
+                $p[$property->getName()] = $property;
             }
         }
         foreach ($this->getProperties()->getGenerator() as $property) {
@@ -403,8 +401,9 @@ public function getAllPropertiesIndexedIterator(): iterable
     public function getParentPropertiesIterator(): iterable
     {
         $p = [];
-        foreach ($this->getParentTypes() as $parentType) {
+        foreach ($this->getRootFirstParentTypes() as $parentType) {
             foreach ($parentType->getProperties()->getGenerator() as $property) {
+                // do not include properties that are overloaded by this type
                 if (!$this->_properties->hasProperty($property->getName()) && !isset($p[$property->getName()])) {
                     $p[$property->getName()] = $property;
                 }
@@ -427,6 +426,14 @@ public function getParentTypes(): array
         return $parents;
     }
 
+    /**
+     * @return \DCarbone\PHPFHIR\Version\Definition\Type[]
+     */
+    public function getRootFirstParentTypes(): array
+    {
+        return array_reverse($this->getParentTypes());
+    }
+
     /**
      * @return bool
      */
@@ -852,6 +859,14 @@ public function getDirectlyUsedTraits(): array
                 ->getFullyQualifiedNamespace(false);
         }
 
+        if (($this->isValueContainer()
+                || $this->getKind()->isOneOf(TypeKindEnum::LIST, TypeKindEnum::PRIMITIVE, TypeKindEnum::PRIMITIVE_CONTAINER))
+            && !($this->hasValueContainerParent() || $this->hasPrimitiveContainerParent() || $this->hasPrimitiveParent())) {
+            $traits[PHPFHIR_ENCODING_TRAIT_XML_LOCATION] = $coreFiles
+                ->getCoreFileByEntityName(PHPFHIR_ENCODING_TRAIT_XML_LOCATION)
+                ->getFullyQualifiedNamespace(false);
+        }
+
         return $traits;
     }
 
diff --git a/template/core/class_factory_config.php b/template/core/class_factory_config.php
index 026f6106..71d810cc 100644
--- a/template/core/class_factory_config.php
+++ b/template/core/class_factory_config.php
@@ -48,12 +48,10 @@ final class <?php echo PHPFHIR_CLASSNAME_FACTORY_CONFIG; ?>
      * <?php echo PHPFHIR_CLASSNAME_FACTORY_CONFIG; ?> Constructor
      * @param array $config
      */
-    public function __construct(array $config = [])
+    public function __construct(null|iterable $versions = null)
     {
-        foreach(<?php echo PHPFHIR_ENUM_FACTORY_CONFIG_KEY; ?>::cases() as $k) {
-            if (isset($config[$k->value]) || array_key_exists($k->value, $config)) {
-                $this->{"set{$k->value}"}($config[$k->value]);
-            }
+        if (null !== $versions) {
+            $this->setVersions(...$versions);
         }
     }
 
@@ -111,10 +109,10 @@ public function getVersion(string $name): null|<?php echo PHPFHIR_CLASSNAME_FACT
     /**
      * Define all versions at once.  Will overwrite any existing versions.
      *
-     * @param array|<?php echo $factVersionConfigClass->getFullyQualifiedName(true); ?>[] $versions Array of version configurations.
+     * @param array|<?php echo $factVersionConfigClass->getFullyQualifiedName(true); ?> ...$versions Array of version configurations.
      * @return self
      */
-    public function setVersions(array $versions): self
+    public function setVersions(array|<?php echo PHPFHIR_CLASSNAME_FACTORY_VERSION_CONFIG; ?> ...$versions): self
     {
         $this->_versions = [];
         foreach($versions as $config) {
@@ -124,15 +122,23 @@ public function setVersions(array $versions): self
     }
 
     /**
-     * Return iterator containing all registered versions.
+     * Returns iterator containing all registered versions.
      *
      * @return \ArrayIterator<<?php echo $factVersionConfigClass->getFullyQualifiedName(true); ?>>
      */
     public function getVersionsIterator(): iterable
     {
+        if ([] === $this->_versions) {
+            return new \EmptyIterator();
+        }
         return new \ArrayIterator($this->_versions);
     }
 
+    /**
+     * Produces generator over all registered versions.
+     *
+     * @return \Generator<?php echo $factVersionConfigClass->getFullyQualifiedName(true); ?>>
+     */
     public function getVersionsGenerator(): \Generator
     {
         foreach($this->_versions as $version) {
diff --git a/template/core/class_version_config.php b/template/core/class_version_config.php
index caa05b74..4fe2e583 100644
--- a/template/core/class_version_config.php
+++ b/template/core/class_version_config.php
@@ -57,27 +57,27 @@ class <?php echo PHPFHIR_CLASSNAME_VERSION_CONFIG; ?> implements <?php echo PHPF
     ];
 
     /** @var <?php echo $unserializeConfigClass->getFullyQualifiedName(true); ?> */
-    private <?php echo PHPFHIR_ENCODING_CLASSNAME_UNSERIALIZE_CONFIG; ?> $unserializeConfig;
+    private <?php echo PHPFHIR_ENCODING_CLASSNAME_UNSERIALIZE_CONFIG; ?> $_unserializeConfig;
 
     /** @var <?php echo $serializeConfigClass->getFullyQualifiedName(true); ?> */
-    private <?php echo PHPFHIR_ENCODING_CLASSNAME_SERIALIZE_CONFIG; ?> $serializeConfig;
+    private <?php echo PHPFHIR_ENCODING_CLASSNAME_SERIALIZE_CONFIG; ?> $_serializeConfig;
 
     /**
      * <?php echo PHPFHIR_CLASSNAME_VERSION_CONFIG; ?> constructor.
-     * @param array $config
+     * @param null|array|<?php echo $serializeConfigClass->getFullyQualifiedName(true); ?> $serializeConfig
+     * @param null|array|<?php echo $unserializeConfigClass->getFullyQualifiedName(true); ?> $unserializeConfig
      */
-    public function __construct(array $config = [])
+    public function __construct(null|array|<?php echo $unserializeConfigClass->getEntityName(); ?> $unserializeConfig = null,
+                                null|array|<?php echo $serializeConfigClass->getEntityName(); ?> $serializeConfig = null)
     {
-        foreach(<?php echo PHPFHIR_ENUM_VERSION_CONFIG_KEY; ?>::cases() as $k) {
-            if (isset($config[$k->value]) || array_key_exists($k->value, $config)) {
-                $this->{"set{$k->value}"}($config[$k->value]);
-            }
-        }
-
-        if (!isset($this->_unserializeConfig)) {
+        if (null !== $unserializeConfig) {
+            $this->setUnserializeConfig($unserializeConfig);
+        } else {
             $this->setUnserializeConfig(self::_DEFAULT_UNSERIALIZE_CONFIG);
         }
-        if (!isset($this->_serializeConfig)) {
+        if (null !== $serializeConfig) {
+            $this->setSerializeConfig($serializeConfig);
+        } else {
             $this->setSerializeConfig(self::_DEFAULT_SERIALIZE_CONFIG);
         }
     }
@@ -89,9 +89,12 @@ public function __construct(array $config = [])
     public function setUnserializeConfig(array|<?php echo PHPFHIR_ENCODING_CLASSNAME_UNSERIALIZE_CONFIG; ?> $config): self
     {
         if (is_array($config)) {
-            $config = new <?php echo PHPFHIR_ENCODING_CLASSNAME_UNSERIALIZE_CONFIG; ?>($config);
+            $config = new <?php echo PHPFHIR_ENCODING_CLASSNAME_UNSERIALIZE_CONFIG; ?>(
+                libxmlOpts: $config['libxmlOpts'] ?? null,
+                jsonDecodeMaxDepth: $config['jsonDecodeMaxDepth'] ?? null,
+            );
         }
-        $this->unserializeConfig = $config;
+        $this->_unserializeConfig = $config;
         return $this;
     }
 
@@ -102,7 +105,7 @@ public function setUnserializeConfig(array|<?php echo PHPFHIR_ENCODING_CLASSNAME
     public function getUnserializeConfig(): <?php echo PHPFHIR_ENCODING_CLASSNAME_UNSERIALIZE_CONFIG; ?>
 
     {
-        return $this->unserializeConfig;
+        return $this->_unserializeConfig;
     }
 
     /**
@@ -112,9 +115,13 @@ public function getUnserializeConfig(): <?php echo PHPFHIR_ENCODING_CLASSNAME_UN
     public function setSerializeConfig(array|<?php echo PHPFHIR_ENCODING_CLASSNAME_SERIALIZE_CONFIG; ?> $config): self
     {
         if (is_array($config)) {
-            $config = new <?php echo PHPFHIR_ENCODING_CLASSNAME_SERIALIZE_CONFIG; ?>($config);
+            $config = new <?php echo PHPFHIR_ENCODING_CLASSNAME_SERIALIZE_CONFIG; ?>(
+                overrideSourceXMLNS: $config['overrideSourceXMLNS'] ?? null,
+                rootXMLNS: $config['rootXMLNS'] ?? null,
+                libxmlOpts: $config['libxmlOpts'] ?? null,
+            );
         }
-        $this->serializeConfig = $config;
+        $this->_serializeConfig = $config;
         return $this;
     }
 
@@ -125,7 +132,7 @@ public function setSerializeConfig(array|<?php echo PHPFHIR_ENCODING_CLASSNAME_S
     public function getSerializeConfig(): <?php echo PHPFHIR_ENCODING_CLASSNAME_SERIALIZE_CONFIG; ?>
 
     {
-        return $this->serializeConfig;
+        return $this->_serializeConfig;
     }
 }
 <?php return ob_get_clean();
diff --git a/template/core/client/class_request.php b/template/core/client/class_request.php
index babf5bcc..f5876bf6 100644
--- a/template/core/client/class_request.php
+++ b/template/core/client/class_request.php
@@ -50,11 +50,15 @@ class <?php echo PHPFHIR_CLIENT_CLASSNAME_REQUEST; ?>
     /** @var string */
     public string $at;
 
-    /** @var <?php echo $formatEnum->getFullyQualifiedName(true); ?> */
-    public <?php echo PHPFHIR_CLIENT_ENUM_RESPONSE_FORMAT; ?> $format;
+    /**
+     * The serialization type to request from the server.  Typically this is 'json' or 'xml'.
+     *
+     * @var string
+     */
+    public string $format;
 
-    /** @var <?php echo $sortEnum->getFullyQualifiedName(true); ?> */
-    public <?php echo PHPFHIR_CLIENT_ENUM_SORT_DIRECTION; ?> $sort;
+    /** @var string */
+    public string $sort;
 
     /**
      * Extra query parameters.
@@ -81,5 +85,44 @@ class <?php echo PHPFHIR_CLIENT_CLASSNAME_REQUEST; ?>
      * @var array
      */
     public array $options;
+
+    public function __construct(string|<?php echo PHPFHIR_CLIENT_ENUM_HTTP_METHOD; ?> $method,
+                                string $path,
+                                null|int $count = null,
+                                null|string $since = null,
+                                null|string $at = null,
+                                null|string|<?php echo PHPFHIR_CLIENT_ENUM_RESPONSE_FORMAT; ?> $format = null,
+                                null|string|<?php echo PHPFHIR_CLIENT_ENUM_SORT_DIRECTION; ?> $sort = null,
+                                null|array $queryParams = null,
+                                null|bool $parseResponseHeaders = null,
+                                null|array $options = null)
+    {
+        $this->method = (string)$method;
+        $this->path = $path;
+        if (null !== $count) {
+            $this->count = $count;
+        }
+        if (null !== $since) {
+            $this->since = $since;
+        }
+        if (null !== $at) {
+            $this->at = $at;
+        }
+        if (null !== $format) {
+            $this->format = (string)$format;
+        }
+        if (null !== $sort) {
+            $this->sort = (string)$sort;
+        }
+        if (null !== $queryParams) {
+            $this->queryParams = $queryParams;
+        }
+        if (null !== $parseResponseHeaders) {
+            $this->parseResponseHeaders = $parseResponseHeaders;
+        }
+        if (null !== $options) {
+            $this->options = $options;
+        }
+    }
 }
 <?php return ob_get_clean();
\ No newline at end of file
diff --git a/template/core/encoding/class_serialize_config.php b/template/core/encoding/class_serialize_config.php
index 5da91474..f6727515 100644
--- a/template/core/encoding/class_serialize_config.php
+++ b/template/core/encoding/class_serialize_config.php
@@ -37,12 +37,18 @@ class <?php echo PHPFHIR_ENCODING_CLASSNAME_SERIALIZE_CONFIG; ?>
     /** @var int */
     private int $_xhtmlLibxmlOpts;
 
-    public function __construct(array $config)
+    public function __construct(null|bool $overrideSourceXMLNS = null,
+                                null|string $rootXMLNS = null,
+                                null|int $xhtmlLibxmlOpts = null)
     {
-        foreach(<?php echo PHPFHIR_ENCODING_ENUM_SERIALIZE_CONFIG_KEY; ?>::cases() as $k) {
-            if (isset($config[$k->value]) || array_key_exists($k->value, $config)) {
-                $this->{"set{$k->value}"}($config[$k->value]);
-            }
+        if (null !== $overrideSourceXMLNS) {
+            $this->setOverrideSourceXMLNS($overrideSourceXMLNS);
+        }
+        if (null !== $rootXMLNS) {
+            $this->setRootXMLNS($rootXMLNS);
+        }
+        if (null !== $xhtmlLibxmlOpts) {
+            $this->setXHTMLLibxmlOpts($xhtmlLibxmlOpts);
         }
     }
 
diff --git a/template/core/encoding/class_unserialize_config.php b/template/core/encoding/class_unserialize_config.php
index b01b09f4..c27790b7 100644
--- a/template/core/encoding/class_unserialize_config.php
+++ b/template/core/encoding/class_unserialize_config.php
@@ -35,12 +35,14 @@ class <?php echo PHPFHIR_ENCODING_CLASSNAME_UNSERIALIZE_CONFIG; ?>
     /** @var int */
     private int $_jsonDecodeMaxDepth;
 
-    public function __construct(array $config)
+    public function __construct(null|int $libxmlOpts = null,
+                                null|int $jsonDecodeMaxDepth = null)
     {
-        foreach(<?php echo PHPFHIR_ENCODING_ENUM_UNSERIALIZE_CONFIG_KEY; ?>::cases() as $k) {
-            if (isset($config[$k->value]) || array_key_exists($k->value, $config)) {
-                $this->{"set{$k->value}"}($config[$k->value]);
-            }
+        if (null !== $libxmlOpts) {
+            $this->setLibxmlOpts($libxmlOpts);
+        }
+        if (null !== $jsonDecodeMaxDepth) {
+            $this->setJsonDecodeMaxDepth($jsonDecodeMaxDepth);
         }
     }
 
diff --git a/template/core/encoding/enum_serialize_config_key.php b/template/core/encoding/enum_serialize_config_key.php
deleted file mode 100644
index e0602767..00000000
--- a/template/core/encoding/enum_serialize_config_key.php
+++ /dev/null
@@ -1,36 +0,0 @@
-<?php declare(strict_types=1);
-
-/*
- * Copyright 2024-2025 Daniel Carbone (daniel.p.carbone@gmail.com)
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-/** @var \DCarbone\PHPFHIR\Config $config */
-/** @var \DCarbone\PHPFHIR\CoreFile $coreFile */
-
-ob_start();
-echo '<?php ';?>declare(strict_types=1);
-
-namespace <?php echo $coreFile->getFullyQualifiedNamespace(false); ?>;
-
-<?php echo $config->getBasePHPFHIRCopyrightComment(false); ?>
-
-
-enum <?php echo PHPFHIR_ENCODING_ENUM_SERIALIZE_CONFIG_KEY; ?> : string
-{
-    case OVERRIDE_SOURCE_XMLNS = 'overrideSourceXMLNS';
-    case ROOT_XMLNS = 'rootXMLNS';
-    case XHTML_LIBXML_OPTS = 'xhtmlLibxmlOpts';
-}
-<?php return ob_get_clean();
\ No newline at end of file
diff --git a/template/core/encoding/enum_unserialize_config_key.php b/template/core/encoding/enum_unserialize_config_key.php
deleted file mode 100644
index 8d043e77..00000000
--- a/template/core/encoding/enum_unserialize_config_key.php
+++ /dev/null
@@ -1,35 +0,0 @@
-<?php declare(strict_types=1);
-
-/*
- * Copyright 2024-2025 Daniel Carbone (daniel.p.carbone@gmail.com)
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-/** @var \DCarbone\PHPFHIR\Config $config */
-/** @var \DCarbone\PHPFHIR\CoreFile $coreFile */
-
-ob_start();
-echo '<?php ';?>declare(strict_types=1);
-
-namespace <?php echo $coreFile->getFullyQualifiedNamespace(false); ?>;
-
-<?php echo $config->getBasePHPFHIRCopyrightComment(false); ?>
-
-
-enum <?php echo PHPFHIR_ENCODING_ENUM_UNSERIALIZE_CONFIG_KEY; ?> : string
-{
-    case LIBXML_OPTS = 'libxmlOpts';
-    case JSON_DECODE_MAX_DEPTH = 'jsonDecodeMaxDepth';
-}
-<?php return ob_get_clean();
\ No newline at end of file
diff --git a/template/core/enum_factory_config_key.php b/template/core/encoding/trait_xml_location.php
similarity index 51%
rename from template/core/enum_factory_config_key.php
rename to template/core/encoding/trait_xml_location.php
index 0e6b07e2..f5f6476c 100644
--- a/template/core/enum_factory_config_key.php
+++ b/template/core/encoding/trait_xml_location.php
@@ -16,10 +16,16 @@
  * limitations under the License.
  */
 
+
 /** @var \DCarbone\PHPFHIR\Config $config */
 /** @var \DCarbone\PHPFHIR\CoreFile $coreFile */
 
+$coreFiles = $config->getCoreFiles();
+
+$xmlLocationEnum = $coreFiles->getCoreFileByEntityName(PHPFHIR_ENCODING_ENUM_XML_LOCATION);
+
 ob_start();
+
 echo '<?php ';?>declare(strict_types=1);
 
 namespace <?php echo $coreFile->getFullyQualifiedNamespace(false); ?>;
@@ -27,9 +33,29 @@
 <?php echo $config->getBasePHPFHIRCopyrightComment(false); ?>
 
 
-enum <?php echo PHPFHIR_ENUM_FACTORY_CONFIG_KEY; ?> : string
+trait <?php echo PHPFHIR_ENCODING_TRAIT_XML_LOCATION; ?>
+
 {
-    case VERSIONS = 'versions';
+    private <?php echo PHPFHIR_ENCODING_ENUM_XML_LOCATION; ?> $_xmlLocation;
+
+    /**
+     * Set the XML location of this element's value when serializing
+     *
+     * @param <?php echo $xmlLocationEnum->getFullyQualifiedName(true); ?> $xmlLocation
+     */
+    public function setXMLLocation(<?php echo PHPFHIR_ENCODING_ENUM_XML_LOCATION; ?> $xmlLocation): void
+    {
+        $this->_xmlLocation = $xmlLocation;
+    }
+
+    /**
+     * @return null|<?php echo $xmlLocationEnum->getFullyQualifiedName(true); ?>
+
+     */
+    public function getXMLLocation(): null|<?php echo PHPFHIR_ENCODING_ENUM_XML_LOCATION; ?>
+
+    {
+        return $this->_xmlLocation ?? null;
+    }
 }
-
-<?php return ob_get_clean();
\ No newline at end of file
+<?php return ob_get_clean();
diff --git a/template/core/enum_version_config_key.php b/template/core/enum_version_config_key.php
deleted file mode 100644
index 4aafa982..00000000
--- a/template/core/enum_version_config_key.php
+++ /dev/null
@@ -1,35 +0,0 @@
-<?php declare(strict_types=1);
-
-/*
- * Copyright 2024-2025 Daniel Carbone (daniel.p.carbone@gmail.com)
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-/** @var \DCarbone\PHPFHIR\Config $config */
-/** @var \DCarbone\PHPFHIR\CoreFile $coreFile */
-
-ob_start();
-echo '<?php ';?>declare(strict_types=1);
-
-namespace <?php echo $coreFile->getFullyQualifiedNamespace(false); ?>;
-
-<?php echo $config->getBasePHPFHIRCopyrightComment(false); ?>
-
-
-enum <?php echo PHPFHIR_ENUM_VERSION_CONFIG_KEY; ?> : string
-{
-    case UNSERIALIZE_CONFIG = 'unserializeConfig';
-    case SERIALIZE_CONFIG = 'serializeConfig';
-}
-<?php return ob_get_clean();
\ No newline at end of file
diff --git a/template/core/interface_comment_container.php b/template/core/interface_comment_container.php
index 1f97276d..54b860d4 100644
--- a/template/core/interface_comment_container.php
+++ b/template/core/interface_comment_container.php
@@ -31,21 +31,24 @@ interface <?php echo PHPFHIR_INTERFACE_COMMENT_CONTAINER; ?>
 
 {
     /**
-     * Arbitrary comments of a hopefully useful nature
-     * @return array
+     * Return any / all comments set on this type.
+     *
+     * @return string[]
      */
     public function _getFHIRComments(): array;
 
     /**
      * Set internal fhir_comments list, overwriting any previous value(s)
+     *
      * @param array $fhirComments
      */
     public function _setFHIRComments(array $fhirComments): void;
 
     /**
      * Append comment string to internal fhir_comments list
+     *
      * @param string $fhirComment
      */
     public function _addFHIRComment(string $fhirComment): void;
 }
-<?php return ob_get_clean();
\ No newline at end of file
+<?php return ob_get_clean();
diff --git a/template/core/interface_contained_type.php b/template/core/interface_contained_type.php
index 88140f79..81db6405 100644
--- a/template/core/interface_contained_type.php
+++ b/template/core/interface_contained_type.php
@@ -39,6 +39,7 @@ interface <?php echo PHPFHIR_INTERFACE_CONTAINED_TYPE; ?> extends <?php echo PHP
 {
     /**
      * The return from this method is used only when json serializing this type
+     *
      * @return string
      */
     public function _getResourceType(): string;
diff --git a/template/core/interface_primitive_type.php b/template/core/interface_primitive_type.php
index 514558b4..3ff4fe31 100644
--- a/template/core/interface_primitive_type.php
+++ b/template/core/interface_primitive_type.php
@@ -32,6 +32,7 @@ interface <?php echo PHPFHIR_INTERFACE_PRIMITIVE_TYPE; ?> extends <?php echo PHP
 {
     /**
      * Must return the appropriate "formatted" stringified version of this primitive type's value
+     *
      * @return string
      */
     public function getFormattedValue(): string;
diff --git a/template/core/interface_type.php b/template/core/interface_type.php
index 2341d791..7d0f093e 100644
--- a/template/core/interface_type.php
+++ b/template/core/interface_type.php
@@ -50,6 +50,7 @@ interface <?php echo PHPFHIR_INTERFACE_TYPE; ?> extends \JsonSerializable
 {
     /**
      * Returns the FHIR name represented by this Type
+     *
      * @return string
      */
     public function _getFHIRTypeName(): string;
@@ -64,6 +65,7 @@ public function _getSourceXMLNS(): null|string;
 
     /**
      * Must return an associative array in structure ["field" => ["rule" => {constraint}]] to be used during validation
+     *
      * @return array
      */
     public function _getValidationRules(): array;
@@ -71,6 +73,7 @@ public function _getValidationRules(): array;
     /**
      * Must return associative array where, if there are validation errors, the keys are the names of fields within the
      * type that failed validation.  The value must be a string message describing the manner of error
+     *
      * @return array
      */
     public function _getValidationErrors(): array;
@@ -81,7 +84,7 @@ public function _getValidationErrors(): array;
      * @param null|<?php echo $unserializeConfigClass->getFullyQualifiedName(true); ?> $config
      * @return null|static
      */
-    public static function xmlUnserialize(null|string|\SimpleXMLElement $element, null|<?php echo PHPFHIR_INTERFACE_TYPE; ?> $type = null, null|<?php echo PHPFHIR_ENCODING_CLASSNAME_UNSERIALIZE_CONFIG ?> $config = null): null|self;
+    public static function xmlUnserialize(string|\SimpleXMLElement $element, null|<?php echo PHPFHIR_INTERFACE_TYPE; ?> $type = null, null|<?php echo PHPFHIR_ENCODING_CLASSNAME_UNSERIALIZE_CONFIG ?> $config = null): null|self;
 
     /**
      * @param null|<?php echo $xmlWriterClass->getFullyQualifiedName(true); ?> $xw
@@ -89,7 +92,7 @@ public static function xmlUnserialize(null|string|\SimpleXMLElement $element, nu
      * @return <?php echo $xmlWriterClass->getFullyQualifiedName(true); ?>
 
      */
-    public function xmlSerialize(null|<?php echo PHPFHIR_ENCODING_CLASSNAME_XML_WRITER; ?> $xw = null, null|<?php echo PHPFHIR_ENCODING_CLASSNAME_SERIALIZE_CONFIG; ?> $config = null): <?php echo PHPFHIR_ENCODING_CLASSNAME_XML_WRITER; ?>;
+    public function xmlSerialize(<?php echo PHPFHIR_ENCODING_CLASSNAME_XML_WRITER; ?> $xw = null, null|<?php echo PHPFHIR_ENCODING_CLASSNAME_SERIALIZE_CONFIG; ?> $config = null): <?php echo PHPFHIR_ENCODING_CLASSNAME_XML_WRITER; ?>;
 
     /**
      * @return string
diff --git a/template/core/interface_version.php b/template/core/interface_version.php
index b66cc9ca..fe77c041 100644
--- a/template/core/interface_version.php
+++ b/template/core/interface_version.php
@@ -48,24 +48,28 @@ interface <?php echo PHPFHIR_INTERFACE_VERSION; ?>
 {
     /**
      * Must return the "name" of this version, e.g. DSTU1, STU3, R5, etc.
+     *
      * @return string
      */
     public function getName(): string;
 
     /**
      * Must return source's reported version of FHIR
+     *
      * @return string
      */
     public function getSourceVersion(): string;
 
     /**
      * Must return the date this FHIR version's source was generated
+     *
      * @return string
      */
     public function getSourceGenerationDate(): string;
 
     /**
      * Must return config for this version
+     *
      * @return <?php echo $versionConfigInterface->getFullyQualifiedName(true); ?>
 
      */
@@ -73,6 +77,7 @@ public function getConfig(): <?php echo PHPFHIR_INTERFACE_VERSION_CONFIG; ?>;
 
     /**
      * Must return the type map class for this version
+     *
      * @return <?php echo $versionTypeMapInterface->getFullyQualifiedName(true); ?>
 
      */
diff --git a/template/core/interface_version_config.php b/template/core/interface_version_config.php
index 0c4eafd6..236fdf03 100644
--- a/template/core/interface_version_config.php
+++ b/template/core/interface_version_config.php
@@ -47,6 +47,7 @@ interface <?php echo PHPFHIR_INTERFACE_VERSION_CONFIG; ?>
 {
     /**
      * Must return the unserialization config to use for this version
+     *
      * @return <?php echo $unserializeConfigClass->getFullyQualifiedName(true); ?>
 
      */
@@ -54,6 +55,7 @@ public function getUnserializeConfig(): <?php echo PHPFHIR_ENCODING_CLASSNAME_UN
 
     /**
      * Must return the serialization config to use for this version
+     *
      * @return <?php echo $serializeConfigClass->getFullyQualifiedName(true); ?>
      */
     public function getSerializeConfig(): <?php echo PHPFHIR_ENCODING_CLASSNAME_SERIALIZE_CONFIG; ?>;
diff --git a/template/core/interface_version_type_map.php b/template/core/interface_version_type_map.php
index 24476954..0a76e5a3 100644
--- a/template/core/interface_version_type_map.php
+++ b/template/core/interface_version_type_map.php
@@ -35,7 +35,8 @@ interface <?php echo PHPFHIR_INTERFACE_VERSION_TYPE_MAP; ?>
 
 {
     /**
-     * Must return the fully qualified class name for FHIR Type name.  Must return null if type not found
+     * Must return the fully qualified class name for FHIR Type name.  Must return null if type not found.
+     *
      * @param string $typeName
      * @return string|null
      */
@@ -43,12 +44,14 @@ public static function getTypeClassName(string $typeName): null|string;
 
     /**
      * Must return the full internal class map
+     *
      * @return array
      */
     public static function getMap(): array;
 
     /**
      * Must return the full list of containable resource types
+     *
      * @return array
      */
     public static function getContainableTypes(): array;
@@ -61,6 +64,7 @@ public static function getContainedTypeClassName(string $typeName): null|string;
 
     /**
      * Must attempt to determine if the provided value is or describes a containable resource type
+     *
      * @param string|array|\SimpleXMLElement|<?php echo $typeInterface->getFullyQualifiedName(true); ?> $type
      * @return bool
      * @throws \InvalidArgumentException
diff --git a/template/core/trait_comment_container.php b/template/core/trait_comment_container.php
index 6beec158..d67bc866 100644
--- a/template/core/trait_comment_container.php
+++ b/template/core/trait_comment_container.php
@@ -34,8 +34,9 @@ trait <?php echo PHPFHIR_TRAIT_COMMENT_CONTAINER; ?>
     private array $_fhirComments = [];
 
     /**
-     * Arbitrary comments of a hopefully useful nature
-     * @return array
+     * Return any / all comments set on this type.
+     *
+     * @return string[]
      */
     public function _getFHIRComments(): array
     {
@@ -44,6 +45,7 @@ public function _getFHIRComments(): array
 
     /**
      * Set internal fhir_comments list, overwriting any previous value(s)
+     *
      * @param array $fhirComments
      */
     public function _setFHIRComments(array $fhirComments): void
@@ -53,6 +55,7 @@ public function _setFHIRComments(array $fhirComments): void
 
     /**
      * Append comment string to internal fhir_comments list
+     *
      * @param string $fhirComment
      */
     public function _addFHIRComment(string $fhirComment): void
@@ -61,4 +64,4 @@ public function _addFHIRComment(string $fhirComment): void
     }
 }
 <?php
-return ob_get_clean();
\ No newline at end of file
+return ob_get_clean();
diff --git a/template/versions/types/class_default.php b/template/versions/types/class_default.php
index 8248d77d..bde03e1d 100644
--- a/template/versions/types/class_default.php
+++ b/template/versions/types/class_default.php
@@ -93,13 +93,8 @@
 endif;
 
 // -- end field properties
-?>
-<?php if ($type->hasLocalProperties()) : ?>
 
-    /** @var array */
-    private array $_xmlLocations = [];
-<?php endif; ?>
-<?php echo require_with(
+echo require_with(
     PHPFHIR_TEMPLATE_VERSION_TYPES_METHODS_DIR . DIRECTORY_SEPARATOR . 'constructor.php',
     [
         'version' => $version,
diff --git a/template/versions/types/methods/constructor.php b/template/versions/types/methods/constructor.php
index 0cf68f51..427259a0 100644
--- a/template/versions/types/methods/constructor.php
+++ b/template/versions/types/methods/constructor.php
@@ -22,6 +22,9 @@
 /** @var \DCarbone\PHPFHIR\Version $version */
 /** @var \DCarbone\PHPFHIR\Version\Definition\Type $type */
 
+$coreFiles = $version->getConfig()->getCoreFiles();
+$xmlLocationEnum = $coreFiles->getCoreFileByEntityName(PHPFHIR_ENCODING_ENUM_XML_LOCATION);
+
 $typeKind = $type->getKind();
 $typeClassName = $type->getClassName();
 $typeImports = $type->getImports();
@@ -47,10 +50,13 @@
     /**
      * <?php echo $typeClassName; ?> Constructor
      * @param <?php echo TypeHintUtils::primitivePHPValueTypeSetterDoc($version, $primitiveType, true, false); ?> $value
+     * @param <?php echo $xmlLocationEnum->getFullyQualifiedName(true); ?> $xmlLocation
      */
-    public function __construct(<?php echo TypeHintUtils::buildSetterParameterHint($version, $valueProperty, true); ?> $value = null)
+    public function __construct(<?php echo TypeHintUtils::buildSetterParameterHint($version, $valueProperty, true); ?> $value = null,
+                                <?php echo $xmlLocationEnum->getEntityName(); ?> $xmlLocation = <?php echo $xmlLocationEnum->getEntityName(); ?>::ATTRIBUTE)
     {
-        $this->setValue($value);
+        $this->setValue(value: $value);
+        $this->setXMLLocation($xmlLocation);
     }
 <?php
     endif;
@@ -58,41 +64,42 @@ public function __construct(<?php echo TypeHintUtils::buildSetterParameterHint($
 
     /**
      * <?php echo $typeClassName; ?> Constructor
-<?php if ($type->isValueContainer()) : ?>
-     * @param <?php echo TypeHintUtils::buildSetterParameterDocHint($version, $valueProperty, true); ?> $value
-<?php endif; ?>
 <?php foreach($type->getAllPropertiesIndexedIterator() as $property) :
-        $pt = $property->getValueFHIRType();
-        if ($type->isValueContainer() && $property->isValueProperty()) {
-            continue;
-        }
-        ?>
+        $pt = $property->getValueFHIRType(); ?>
      * @param <?php echo TypeHintUtils::buildSetterParameterDocHint($version, $property, true); ?> $<?php echo $property->getName(); ?>
 
 <?php endforeach; if ($type->hasCommentContainerParent() || $type->isCommentContainer()) : ?>
      * @param null|iterable $fhirComments
+<?php endif;
+if ($type->isValueContainer() || $type->hasValueContainerParent() || $type->hasPrimitiveContainerParent() || $typeKind === TypeKindEnum::PRIMITIVE_CONTAINER) : ?>
+    * @param <?php echo $xmlLocationEnum->getFullyQualifiedName(true); ?> $xmlLocation
 <?php endif; ?>     */
-    public function __construct(<?php if ($type->isValueContainer()) : echo TypeHintUtils::buildSetterParameterHint($version, $valueProperty, true);?> $value = null<?php endif;
-    foreach($type->getAllPropertiesIndexedIterator() as $i => $property) :
-        if ($type->isValueContainer() && $property->isValueProperty()) {
-            continue;
-        }
-        if ($type->isValueContainer() || $i > 0) : ?>,
+    public function __construct(<?php foreach($type->getAllPropertiesIndexedIterator() as $i => $property) : if ($i > 0) : ?>,
                                 <?php endif; echo TypeHintUtils::buildSetterParameterHint($version, $property, true); ?> $<?php echo $property->getName(); ?> = null<?php endforeach;
                                 if ($type->hasCommentContainerParent() || $type->isCommentContainer()) : if ($totalPropertyCount > 0) : ?>,
-                                <?php endif; ?>null|iterable $fhirComments = null<?php endif; ?>)
+                                <?php endif; ?>null|iterable $fhirComments = null<?php endif;
+                                if ($type->isValueContainer() || $type->hasValueContainerParent() || $type->hasPrimitiveContainerParent() || $typeKind === TypeKindEnum::PRIMITIVE_CONTAINER) : ?>,
+                                <?php echo $xmlLocationEnum->getEntityName(); ?> $xmlLocation = <?php echo $xmlLocationEnum->getEntityName(); ?>::<?php if ($type->isValueContainer()) : ?>ELEMENT<?php else : ?>ATTRIBUTE<?php endif; endif; ?>)
     {
 <?php if (null !== $parentType) : ?>
         parent::__construct(<?php foreach($type->getParentPropertiesIterator() as $i => $property) : if ($i > 0) : ?>,
-                            <?php endif; echo $property->getName(); ?>: $<?php echo $property->getName(); ?><?php endforeach; ?><?php if ($type->hasCommentContainerParent()) :
+                            <?php endif; echo $property->getName(); ?>: $<?php echo $property->getName(); ?><?php endforeach; ?><?php
+        if ($type->hasCommentContainerParent()) :
             if ($parentPropertyCount > 0) : ?>,
-                            <?php endif; ?>fhirComments: $fhirComments<?php endif; ?>);
-<?php endif; if (!$type->hasCommentContainerParent() && $type->isCommentContainer()) : ?>
+                            <?php endif; ?>fhirComments: $fhirComments<?php endif;
+                            if ($type->hasValueContainerParent() || $type->hasPrimitiveContainerParent()) :
+                               if ($parentPropertyCount > 0) : ?>,
+                                   <?php endif; echo $xmlLocationEnum->getEntityName(); ?>: $xmlLocation<?php endif; ?>);
+<?php endif;
+if (!$type->hasCommentContainerParent() && $type->isCommentContainer()) : ?>
         if (null !== $fhirComments && [] !== $fhirComments) {
             $this->_setFHIRComments($fhirComments);
-        }<?php endif; ?>
+        }<?php endif;
+if (($type->isValueContainer() || $typeKind === TypeKindEnum::PRIMITIVE_CONTAINER) && !($type->hasPrimitiveContainerParent() || $type->hasValueContainerParent())) : ?>
+        $this->setXMLLocation($xmlLocation);
+<?php endif;
 
-<?php foreach($properties->getGenerator() as $property) :
+foreach($properties->getGenerator() as $property) :
     if ($property->getOverloadedProperty()) {
         continue;
     }
diff --git a/template/versions/types/methods/constructors/default_property_setter_call.php b/template/versions/types/methods/constructors/default_property_setter_call.php
index 948623fd..35d68a35 100644
--- a/template/versions/types/methods/constructors/default_property_setter_call.php
+++ b/template/versions/types/methods/constructors/default_property_setter_call.php
@@ -23,7 +23,7 @@
 ob_start(); ?>
         if (null !== $<?php echo $property->getName(); ?>) {
 <?php if ($property->isCollection()) : ?>
-            $this->set<?php echo $property->getName(); ?>(...$<?php echo $property->getName(); ?>);
+            $this->set<?php echo ucfirst($property->getName()); ?>(...$<?php echo $property->getName(); ?>);
 <?php else : ?>
             $this-><?php echo $property->getSetterName(); ?>($<?php echo $property->getName(); ?>);
 <?php endif; ?>