$errors = drupal_get_messages('error');

// Note: To set a customized error message for a core Drupal field, the first parameter 
// should not be the same value as an identifier for that default Drupal field. i.e. first 
// parameter should not be "title", "body_filter", "field_category" because those are 
// reserved by Drupal.
if (strlen(trim($node->title)) <1){
  form_set_error('title_field','Information Tab: Title is required.');
}

if ($node->field_category['tids'] == 0 ) {
  form_set_error('field_category','Information Tab: Category is required.');
}

if (strlen(trim($node->field_design_problem['0']['value']))<1){
  form_set_error('field_design_problem','Problem Tab: "Design Problem" is required..');
}

if (strlen(trim($node->field_solution[0]['value']))<1){
  form_set_error('field_solution','Solution Tab: "Solution Description" is required.');
}

if (strlen(trim($node->field_how[0]['value']))<1){
  form_set_error('field_how','Solution Tab: "How" is required.');
}

if (strlen(trim($node->field_why[0]['value']))<1){
  form_set_error('field_why','Solution Tab: "Why" is required.');
}

// Check for Solution image attribution and image. Both values should come in pairs.
// If at least one of the pair is missing, notify the user.

if ( (count($node->field_solution_image) < 1)&& 
(strlen(trim($node->field_solution_image_attributio['0']['value'])) < 1) )
{ 
form_set_error('field_image_upload_upload','Solution Tab: Solution image is required.');
  form_set_error('field_solution_image_attributio','Solution Tab: Solution image source is required.');
} else if (count($node->field_solution_image) < 1) {
form_set_error('field_solution_image','Solution Tab: Solution image is required.');
} else if (strlen(trim($node->field_solution_image_attributio['0']['value'])) < 1) {
  form_set_error('field_solution_image_attributio','Solution Tab: Solution image source is required.');
}