diff --git a/src/Schema/Model.php b/src/Schema/Model.php
new file mode 100644
index 0000000..87af424
--- /dev/null
+++ b/src/Schema/Model.php
@@ -0,0 +1,93 @@
+<?php
+
+namespace Twister\Schema;
+
+abstract class Model
+{
+}
+
+namespace Twister;
+
+class Session
+{
+	private static $_db = null;
+
+	function __construct(DB &$db)
+	{
+		session_set_save_handler('Session::open', 'Session::close', 'Session::read', 'Session::write', 'Session::destroy', 'Session::gc');
+		register_shutdown_function('session_write_close');
+		session_set_cookie_params(0, '/', null, true, true);
+		self::$_db = $db;
+		session_start();
+	}
+
+	static function open($sp, $sn)
+	{
+		return true;
+	}
+
+	static function close()
+	{
+		return true;
+	}
+
+	static function read($id)
+	{
+		if (isset($_COOKIE[session_name()]))
+		{
+			if (!ctype_xdigit($id) || strlen($id) !== 32) die('Invalid Session ID: ' . $id);
+			if ($rs = self::$_db->query('SELECT SQL_NO_CACHE data FROM sessions WHERE id = 0x' . $id . ' LIMIT 1'))
+			{
+				$row = $rs->fetch_row();
+				$rs->free_result();
+				return (string) $row[0];
+			}
+		}
+		return '';
+	}
+
+	static function write($id, $data)
+	{
+		if (isset($_COOKIE[session_name()]))	//	WARNING: This will NOT write the session on the first page view! The cookie MUST be created/set first, which requires another page view before it works! This prevents bots from creating sessions! But during testing a new session_id() or browser, it can be confusing because you won't see a new session until your second page view!
+		{
+			$data = empty($data) ? 'NULL' : '"' . self::$_db->real_escape_string($data) . '"';
+			self::$_db->real_query('INSERT INTO sessions (id, timestamp, persistent, data) VALUES (0x' . $id . ', UNIX_TIMESTAMP(), 0, ' . $data . ') ON DUPLICATE KEY UPDATE timestamp = UNIX_TIMESTAMP(), data = ' . $data);
+		}
+		return true;
+	}
+
+	//	This is ONLY required in the login page!
+	static function create_persistent_session()
+	{
+		self::$_db->real_query('INSERT INTO sessions (id, timestamp, persistent, data) VALUES (0x' . session_id() . ', UNIX_TIMESTAMP(), UNIX_TIMESTAMP(), NULL)');
+	}
+
+/*
+	static function login($user_id, $persistent)
+	{
+		session_regenerate_id(true);
+		setcookie(session_name(), session_id(), $persistent ? 0x7fffffff : 0, '/');
+		$_SESSION['id'] = $user_id;
+		self::$_db->real_query('INSERT INTO sessions (id, timestamp, persistent, user_id, data) VALUES (0x' . session_id() . ', UNIX_TIMESTAMP(), ' . ($persistent ? 'UNIX_TIMESTAMP(), ' : '0, ') . $user_id . ', "")');
+	}
+*/
+
+	//	Taken from: http://www.php.net/manual/en/function.session-destroy.php
+	//	`session_destroy() destroys all of the data associated with the current session. It does not unset any of the global variables associated with the session, or unset the session cookie.`
+	static function destroy($id)
+	{
+		self::$_db->real_query('DELETE FROM sessions WHERE id = 0x' . $id);
+		return true;
+	}
+
+	static function gc($ttl)
+	{
+		self::$_db->real_query('DELETE FROM sessions WHERE timestamp < UNIX_TIMESTAMP() - ' . $ttl . ' AND persistent = 0'); // $ttl = 1440 (default) = 24 minutes
+		if (mt_rand(0, 99) == 0)
+		{
+			self::$_db->real_query('OPTIMIZE TABLE sessions');	// optional routine maintenance
+			self::$_db->real_query('FLUSH QUERY CACHE');			// optional routine maintenance
+		}
+		return true;
+	}
+}
diff --git a/src/Schema/Schema.php b/src/Schema/Schema.php
index 7256d99..0bfc4ab 100644
--- a/src/Schema/Schema.php
+++ b/src/Schema/Schema.php
@@ -1,54 +1,88 @@
 <?php
 
-//Twister\Schema::worlds()->id->min
-//Twister\Schema::users()->fields()
+//$schema->worlds->id->min
+//$schema->users()
 
 namespace Twister;
 
 class Schema
 {
-	private static $tables	=	null;
-	private static $db		=	null;
-	private static $schema	=	'DATABASE()';
-	private static $cache	=	null;
+	private $tables			=	null;
+	private $conn			=	null;
+	private $schema			=	null;
+	private $location		=	null;			//	(save) location?	store?	folder?		directory?	cache?
+	private $constraints	=	null;
+	private $lang			=	null;
 
-	//	Set db to MySQL Connection object - if not set, then procedural style will be used
-	public static function setConn($conn)
+	public function __construct($conn = null, $schema = null, $location = null, $constraints = null, $lang = 'en')
 	{
-		self::$db = $conn;
+		$this->setConn($conn)->setSchema($schema)->setLocation($location)->setConstraints($constraints)->setLang($lang);
 	}
 
-	//	Set the database schema name
-	public static function setSchema($schema)
+	public function __get($table)
 	{
-		self::$schema = $schema != 'DATABASE()' ? '"' . $schema . '"' : 'DATABASE()';
-	}
-
-	//	Set the schema cache directory, where we can store files for the composer autoloader
-	public static function setCache($cache)
-	{
-		self::$cache = $cache;
-	}
-
-	public static function __callStatic(string $table, array $args)
-	{
-		if ( ! isset($tables[$table]))
+		if ( ! isset($this->tables[$table]))
 		{
 			try
 			{
-				$class = 'Twister\\Schema\\' . self::toPascalCase($table);
-				$tables[$table] = new $class();
+				$class = 'Twister\\Schema\\Tables\\' . self::toPascalCase($table);
+				$this->tables[$table] = new $class();
 			}
 			catch (\Exception $e)
 			{
-				$tables[$table] = self::build($table);
+				$this->tables[$table] = self::build($table);
 			}
 		}
-		return $tables[$table];
+		return $this->tables[$table];
 	}
 
 	/**
-	 *	Converts $table to PascalCase, preserving leading and trailing underscores '_'
+	 *	Set db to MySQL Connection object - if not set, then procedural style will be used
+	 */
+	public function setConn($conn)
+	{
+		self::$conn = $conn;
+		return $this;
+	}
+
+	/**
+	 *	Set the database schema name
+	 */
+	public function setSchema($schema)
+	{
+		self::$schema = $schema != 'DATABASE()' ? '"' . $schema . '"' : 'DATABASE()';
+		return $this;
+	}
+
+	/**
+	 *	Set the schema cache directory, where we can store files for the composer autoloader
+	 */
+	public static function setLocation($location)
+	{
+		self::$location = $location;
+		return $this;
+	}
+
+	/**
+	 *	Set the schema cache directory, where we can store files for the composer autoloader
+	 */
+	public static function setConstraints($constraints)
+	{
+		self::$location = $location;
+		return $this;
+	}
+
+	/**
+	 *	Set the language used for translations, default is English
+	 */
+	public static function setLang($lang = 'en')
+	{
+		self::$lang = $lang;
+		return $this;
+	}
+
+	/**
+	 *	Helper function to convert $table name to PascalCase, preserving leading and trailing underscores '_'
 	 *	eg. nation_capitals__ => NationCapitals__
 	 */
 	private static function toPascalCase($table)
@@ -56,11 +90,22 @@ class Schema
 		return str_repeat('_', strspn($table, '_')) . str_replace('_', '', ucwords($table, '_')) . str_repeat('_', strspn(strrev($table), '_'));
 	}
 
-	public static function build($table = null, $db = null, string $cache = null)
+	/**
+	 *	Force Table Schema Class (Cache) Rebuild
+	 *	There might be times where we need to force a table rebuild, eg. we change an Enum column at runtime!
+	 */
+	private static function forceRebuild($table)
+	{
+		throw new \Exception('TODO');
+	}
+
+	public function buildSchema($table = null)
 	{
 		mysqli_report( MYSQLI_REPORT_STRICT );
 
-		$cache = $cache ?: self::$cache;
+		if ( ! is_dir($this->location) || ! is_writable($this->location)) {
+			throw new \Exception('Schema cache folder location `' . $this->location . '` must be a valid writable folder to build the table schema!');
+		}
 
 		static $methods = null;
 		if ($methods === null)
diff --git a/src/Schema/Table.php b/src/Schema/Table.php
index e4a1b95..e5f6146 100644
--- a/src/Schema/Table.php
+++ b/src/Schema/Table.php
@@ -4,7 +4,9 @@ namespace Twister\Schema;
 
 abstract class Table
 {
-	protected $fields	=	null;
+	protected	$name	=	null;
+	protected	$hash	=	null;
+	protected	$fields	=	null;
 
 	public function __construct(array $fields = null)
 	{
@@ -13,9 +15,42 @@ abstract class Table
 
 	public function __get($field)
 	{
-		return $this->fields[$field];
+		static $tr = null;
+		static $cache = null;
+
+		if (isset($this->fields[$field]))
+			return $this->fields[$field];
+
+		$old_field = $field;
+/*
+
+		if ( ! isset($cache[$field]))
+		{
+			if ($tr === null)
+			{
+				foreach (range('A', 'Z') as $char)
+					$tr[$char] = '_' . strtolower($char);
+			}
+			$cache[$old_field] = $field = strtr(lcfirst($field), $tr);
+		}
+
+		if (isset($this->fields[$field]))
+			return $this->fields[$field];
+*/
+		throw new \Exception("Table `{$this->name}` doesn't contain a field called `$old_field`");
 	}
 
+
+	public function tableName()
+	{
+		return $this->name;
+	}
+	public function tableHash()
+	{
+		return $this->hash;
+	}
+
+
 	//	$statement = 'UPDATE' | 'INSERT' ... UPDATE = partial check, INSERT = FULL (required non-nullable fields) check!
 	public function validate($statement)
 	{
@@ -30,6 +65,25 @@ abstract class Table
 	{
 		return $this->fields;
 	}
+	public function fieldNames()
+	{
+		return array_keys($this->fields);
+	}
+	public function getFieldNames()
+	{
+		return array_keys($this->fields);
+	}
+
+	//	get an array, with field names as keys, but ALL values set to NULL
+	//	This can be useful for array_merge() to test if ALL the fields in an INSERT statement will be met, including those fields we don't explicitly set! like timestamp = CURRENT_TIMESTAMP / on update CURRENT_TIMESTAMP
+	public function emptyFields()
+	{
+		return array_fill_keys(array_keys($this->fields), null);
+	}
+	public function getEmptyFields()
+	{
+		return array_fill_keys(array_keys($this->fields), null);
+	}
 
 
 }
diff --git a/src/Schema/Types/BaseType.php b/src/Schema/Types/BaseType.php
index 0935e76..ab8d5db 100644
--- a/src/Schema/Types/BaseType.php
+++ b/src/Schema/Types/BaseType.php
@@ -5,7 +5,7 @@ namespace Twister\Schema\Types;
 abstract class BaseType
 {
 	protected $properties	=	null;
-
+/*
 	public function __construct(array $properties)
 	{
 		$properties['type']		=	&$properties[0];
@@ -21,7 +21,7 @@ abstract class BaseType
 		$this->default		=	$default;
 		$this->nullable		=	$nullable;
 	}
-
+*/
 	/**
 	 * Get table field/column property
 	 *
diff --git a/src/Schema/Types/EnumType.php b/src/Schema/Types/EnumType.php
index 2a4a379..7eb281a 100644
--- a/src/Schema/Types/EnumType.php
+++ b/src/Schema/Types/EnumType.php
@@ -4,10 +4,12 @@ namespace Twister\Schema\Types;
 
 class EnumType implements \Iterator, \Countable, \ArrayAccess
 {
-	private $properties	=	null;
-	private $members	=	null;
+	protected $properties	=	null;
+	private $members		=	null;
 
-	private static $isValid = null;	// cache the default isValid function
+	public	$required		=	false;	//	`required` is a publically changeable property (ie. we can override the default, unlike the other properties! moved here because of __set() restrictions)
+
+	private static $isValid	=	null;	//	cache the default `isValid` function
 
 	public function __construct(&$table, $name, $default, $nullable, array $members)
 	{
@@ -17,14 +19,34 @@ class EnumType implements \Iterator, \Countable, \ArrayAccess
 		$this->properties['default']	=	$default;
 		$this->properties['nullable']	=	$nullable;
 
+		$this->required					=	$default === null && ! $nullable;
+
 		if (self::$isValid === null) {
-			self::$isValid = function ($table, $type, $value) { $type };
+			self::$isValid	=	function ($type, $value)
+								{
+									return $value !== null && in_array($value, $type->members) || $value === null && ($type->nullable || $this->default);
+								};	//	in_array(null, ['']) === true	... therefore we MUST test `$value !== null` before the in_array() or we might get false positives
 		}
-		$this->properties['isValid']	=	self::$isValid
+		$this->properties['isValid']	=	self::$isValid;
 
 		$this->members					=	$members;
 	}
 
+	//	Returns an `ALTER TABLE` statement for the $members ... what about the table cache !?!?
+	//	Setting $default to false will remove the default ... alternatively set the default to null !?!?
+	public function alterTable(array $members, $default = null)
+	{
+		//ALTER TABLE `fcm`.`worlds` 
+		//CHANGE COLUMN `type` `type` ENUM('real', 'auto|mated', 'private', 'public', 'invitational', 'scenario', 'campaign', 'archived') NOT NULL DEFAULT 'public' ;
+		//	TODO: $members cannot have any `\` characters! I think they are forbidden in Enums because MySQL removes them!
+		$default = $default ?? $this->properties['default'];
+		$default = $default === false ? null : ($default === null ? ' DEFAULT NULL' : ' DEFAULT \'' . $default . '\'');
+		return 'ALTER TABLE `' . $this->properties['table'] . '`' .
+				' CHANGE COLUMN `' . $this->properties['name'] . '` `' . $this->properties['name'] . '` ENUM(\'' . implode('\', \'', $members) . '\')' . ($this->properties['nullable'] ? ' NULL' : ' NOT NULL') . $default;
+	}
+
+
+
 	/**
 	 * Get table field/column property
 	 *
diff --git a/src/Schema/Types/IntegerType.php b/src/Schema/Types/IntegerType.php
index 238fc27..1769603 100644
--- a/src/Schema/Types/IntegerType.php
+++ b/src/Schema/Types/IntegerType.php
@@ -4,30 +4,48 @@ namespace Twister\Schema\Types;
 
 class IntegerType extends BaseType
 {
-	public $min				=	null;
-	public $max				=	null;
+	protected $properties	=	null;
 
-//	public $auto_increment	=	null;
+	public	$required		=	false;	//	`required` is a publically changeable property (ie. we can override the default, unlike the other properties! moved here because of __set() restrictions)
 
+	private static $isValid =	null;	//	cache the default `isValid` function
+/*
 	private $clamp			=	function ($type, $value) {};	//	callback function for `clamp`
 	private $__invoke		=	function ($type, $value) {};	//	callback function for `__invoke`
 	private $toPHP			=	function ($type, $value) {};	//	callback function for toPHP
 	private $toSQL			=	function ($type, $value) {};	//	callback function for toSQL
 	private $valid			=	function ($type, $value) {};	//	callback function for isValid
-
-	public function __construct($type, $default, $nullable, $min, $max)
+*/
+	public function __construct(&$table, $name, $type, $default, $nullable, $min, $max, $auto = false)
 	{
-		$this->type			=	$type;
-		$this->default		=	$default;
-		$this->nullable		=	$nullable;
+		$this->properties['table']			=	$table;
+		$this->properties['name']			=	$name;
+		$this->properties['type']			=	$type;
+		$this->properties['default']		=	$default;
+		$this->properties['nullable']		=	$nullable;
+		$this->properties['min']			=	$min;
+		$this->properties['max']			=	$max;
+		$this->properties['autoincrement']	=	$auto;
+		$this->properties['unsigned']		=	$min === 0;
 
-		$this->min			=	$min;
-		$this->max			=	$max;
+		$this->required						=	$default === null && ! $nullable && ! $auto;
+
+		if (self::$isValid === null) {
+			self::$isValid	=	function ($type, $value)
+								{
+									return $value !== null && is_string($value) && ($type->charset === 'latin1' ? strlen($value) : mb_strlen($value, 'utf8')) <= $this->maxlength || $value === null && ($type->nullable || $this->default);
+								};	//	in_array(null, ['']) === true	... therefore we MUST test `$value !== null` before the in_array() or we might get false positives
+		}
+		$this->properties['isValid']	=	self::$isValid;
 	}
 
+	public function unsigned()
+	{
+		return $this->min === 0;
+	}
 	public function isUnsigned()
 	{
-		return $this->min >= 0;
+		return $this->min === 0;
 	}
 
 	public function filter($value)
diff --git a/src/Schema/Types/StringType.php b/src/Schema/Types/StringType.php
index 8c50af3..a979c8f 100644
--- a/src/Schema/Types/StringType.php
+++ b/src/Schema/Types/StringType.php
@@ -4,25 +4,34 @@ namespace Twister\Schema\Types;
 
 class StringType extends BaseType
 {
-	const CHARSET_BINARY	= 0;	// unused	(the charset of BINARY fields is NULL!) ... we need to put BINARY data types inside string, for the maxlength ...
-	const CHARSET_LATIN1	= 1;
-	const CHARSET_UTF8		= 3;
-	const CHARSET_UTF8MB4	= 4;
-//	const CHARSET_UTF16		= 16;	// unused
-//	const CHARSET_UTF32		= 32;	// unused
+	protected $properties	=	null;
+
+	public	$required		=	false;	//	`required` is a publically changeable property (ie. we can override the default, unlike the other properties! moved here because of __set() restrictions)
+
+	private static $isValid	=	null;	//	cache the default `isValid` function
+
+	public function __construct(&$table, $name, $type, $default, $nullable, $length, $charset, $fixed = false)
+	{
+		$this->properties['table']		=	$table;
+		$this->properties['name']		=	$name;
+		$this->properties['type']		=	$type;
+		$this->properties['default']	=	$default;
+		$this->properties['nullable']	=	$nullable;
+		$this->properties['length']		=	$length;
+		$this->properties['charset']	=	$charset;
+		$this->properties['fixed']		=	$fixed;		//	fixed length - from Doctrine: `fixed (boolean): Whether a string or binary Doctrine type column has a fixed length. Defaults to false.`
 
-	public $maxlength		= null;
-	public $charset			= null;
 //	public $binary			= null; // needed? could be set by collation type: `utf8_bin` or data type `binary` ???
 
-	function __construct($type, $default, $nullable, $maxlength, $charset)
-	{
-		$this->type			=	$type;
-		$this->default		=	$default;
-		$this->nullable		=	$nullable;
+		$this->required					=	$default === null && ! $nullable;
 
-		$this->maxlength	=	$maxlength;
-		$this->charset		=	$charset;
+		if (self::$isValid === null) {
+			self::$isValid	=	function ($type, $value)
+								{
+									return $value !== null && is_string($value) && ($type->charset === 'latin1' ? strlen($value) : mb_strlen($value, 'utf8')) <= $this->maxlength || $value === null && ($type->nullable || $this->default);
+								};	//	in_array(null, ['']) === true	... therefore we MUST test `$value !== null` before the in_array() or we might get false positives
+		}
+		$this->properties['isValid']	=	self::$isValid;
 	}
 
 	function isValid($value)