'dfpre:' => 'match pre-image git blob ID',
'dfpost:' => 'match post-image git blob ID',
'dfblob:' => 'match either pre or post-image git blob ID',
'dfpre:' => 'match pre-image git blob ID',
'dfpost:' => 'match post-image git blob ID',
'dfblob:' => 'match either pre or post-image git blob ID',