Note: this list is generated by looking for the string for this theme hook, so it may include some references that are not actually using this theme hook.

backdrop_common_theme in includes/common.inc
Provides theme registration for themes across .inc files.
BackdropWebTestCase::handleForm in modules/simpletest/backdrop_web_test_case.php
Handle form input related to backdropPost(). Ensure that the specified fields exist and attempt to create POST data in the correct manner for the particular field type.
comment_form in modules/comment/comment.module
Form constructor for the basic commenting form.
contact_personal_form in modules/contact/contact.pages.inc
Form constructor for the personal contact form.
contact_site_form in modules/contact/contact.pages.inc
Form constructor for the site-wide contact form.
email_field_formatter_info in modules/email/email.module
Implements hook_field_formatter_info().
email_field_formatter_view in modules/email/email.module
Implements hook_field_formatter_view().
email_field_info in modules/email/email.module
Implements hook_field_info().
email_field_is_empty in modules/email/email.module
Implements hook_field_is_empty().
email_field_schema in modules/email/email.install
Implements hook_field_schema().
EmailFieldTestCase::setUp in modules/email/tests/email.test
Sets up a Backdrop site for running functional and integration tests.
EmailFieldTestCase::testEmailField in modules/email/tests/email.test
Tests e-mail field.
email_field_validate in modules/email/email.module
Implements hook_field_validate().
email_field_widget_form in modules/email/email.module
Implements hook_field_widget_form().
email_field_widget_info in modules/email/email.module
Implements hook_field_widget_info().
FieldGetValueTestCase::setUp in modules/field/tests/field.test
Sets up a Backdrop site for running functional and integration tests.
FieldGetValueTestCase::testFieldGetValue in modules/field/tests/field.test
Test field_get_value().
FormEmailTestCase::testFormEmail in modules/simpletest/tests/form.test
Tests that #type 'email' fields are properly validated.
form_test_email in modules/simpletest/tests/form_test.module
Form constructor for testing #type 'email' elements.
_install_configure_form in includes/install.core.inc
Form constructor for a site configuration form.
link.module in modules/link/link.module
Defines simple link field types.
PagePreviewTestCase::setUp in modules/node/tests/node.test
Sets up a Backdrop site for running functional and integration tests.
system_element_info in modules/system/system.module
Implements hook_element_info().
system_requirements in modules/system/system.install
Implements hook_requirements().
system_site_information_settings in modules/system/system.admin.inc
Form builder; The general site information form.
system_update_1041 in modules/system/system.install
Notify administrators if a non-core version of Email module is present.
update_settings in modules/update/update.admin.inc
Form constructor for the update settings form.
user_account_form in modules/user/user.module
Helper function to add default user account fields to user registration and edit form.
user_form_process_password in modules/user/user.module
Form element process handler for client-side password hide/show and strength.
user_settings_email in modules/user/user.admin.inc
Form builder; Configure user email settings for this site.