field_add_more_submit in core/modules/field/field.form.inc

Submit handler for the "Add another" button of a field form.

field_attach_form_validate in core/modules/field/field.attach.inc

Perform field validation against form-submitted field values.

field_default_form in core/modules/field/field.form.inc

Creates a form element for a field and can populate it with a default value.

field_default_form_errors in core/modules/field/field.form.inc

Transfer field-level validation errors to widgets.

field_form_element_after_build in core/modules/field/field.form.inc

#after_build callback for field elements in a form.

field_ui_field_edit_form_validate in core/modules/field_ui/field_ui.admin.inc

Form validation handler for field_ui_field_edit_form().

file_field_widget_submit in core/modules/file/file.field.inc

Form submission handler for upload/remove button of file_field_widget_form().