Does this look right for adding a terms of use checkbox to register form?

Question

And also, how can I get node/terms to open target="_blank"?

<?php


function MYMODULE_form_alter(&$form, $form_state, $form_id) {
    if($form_id == 'user_register') {
  $form['legal'] = array(
      '#type' => 'fieldset',
      '#title' => t('legal'),    
    );
  $form['legal']['select'] = array(
      '#type' => 'checkbox',
      '#required' => TRUE,
      '#title' => t('Terms of Use<span class="form-required" title="' . t('This field is required') . '">*</span>'),
      '#default_value' => 0,
      '#description' => t('I certify that I am over the age of 18, and I have read and agree to the '.l('Terms of use.','node/terms').''),     
    );   
  $form['#validate'][] ='customfunctions_form_validate_custom';
  }  

}  



function MYMODULE_form_validate_custom($form, &$form_state) {
    $legal = $form_state['values']['select'];  
    if ($legal == 0) {
        form_set_error('select', 'Please check the agreement.');
    }
}


?>

Answer 1

Yes, but I would change

$form['#validate'][] ='customfunctions_form_validate_custom';

to

$form['#validate'][] ='MYMODULE_user_registration_form_validate';

and

function MYMODULE_form_validate_custom($form, &$form_state) {

to

function MYMODULE_user_registration_form_validate($form, &$form_state) {

Nothing wrong with your code, but this just keep with the Drupal naming convention ie search_form_validate, node_form_validate, etc

Also

'#title' => t('Terms of Use<span class="form-required" title="' . t('This field is required') . '">*</span>'),

is bad

'#title' => t('Terms of Use') . "<span class='form-required' title='" . t('This field is required') . "'>*</span>",