Update 6.x -> 7.x Conversion Guide re: removal of taxonomy synonyms

Thanks for updating. As you say, for getting equivalent functionality in D7, you would have to add a field to the taxonomy terms in a vocabulary, something like this:

  $field = array(
    'field_name' => 'synonyms_synonym', // The unique machine name used to refer to this field
    'type' => 'text', // Each synonym will be a text string
    'cardinality' => FIELD_CARDINALITY_UNLIMITED, // Allow an unlimited number of synonyms per term
  );
  field_create_field($field);

  $instance = array(
    'field_name' => 'synonyms_synonym', // The field we just created
    'object_type' => 'taxonomy_term',  // The type of node to bind this field to
    'bundle' => 'tags',     // The name of the vocabulary
    'label' => t('Synonyms for this term'),
    'weight' => 0,
    'widget' => array(
      'type' => 'text_textfield',
      'label' => t('Some text'), // Don't know when this gets displayed
    ),
  );
  field_create_instance($instance); 

That doesn't answer the question of an upgrade path from D6 though - I've got two sites that make fairly extensive use of synonyms, and I'm not sure how I'm going to get them from term_synonym table to field API....