Question: Can anyone please tell me how can I add a new column of type enum to my schema in order to implement a Doctrine Migration?

Answer: 
In case you need to write the migration script yourself, here's an example of the syntax -- I haven't found a proper specification for the syntax anywhere.

```
$this->addColumn('tablename', 'column_name', 'enum', false, 
                  array('fixed' => 1,
                        'values' => 
                         array(0 => 'auto',
                               1 => 'manual',
                               2 => 'unknown'),
                         'default' => 'unknown',
                         'notnull' => true,
                         'length' => NULL,
                   ));

```
The simplest way to run it from a Doctrine Migration is to register a new mapping. Then you can enforce values inside your entity if need be. ([Doctrine MySQL Enums](http://docs.doctrine-project.org/projects/doctrine-orm/en/2.1/cookbook/mysql-enums.html))

```
public function up(Schema $schema)
{
    $this->connection->getDatabasePlatform()->registerDoctrineTypeMapping('enum', 'string');
    ...
}

```