12 uses of REQUIREMENT_ERROR in Drupal 6

color_requirements in modules/color/color.install

db_status_report in includes/database.mysqli.inc

Report database status.

db_status_report in includes/database.mysql.inc

Report database status.

db_status_report in includes/database.pgsql.inc

Report database status.

drupal_check_module in includes/install.inc

Check a module's requirements.

install_check_requirements in ./install.php

Check installation requirements and report any errors.

system_requirements in modules/system/system.install

Implementation of hook_requirements().

system_status in modules/system/system.admin.inc

Menu callback: displays the site status report. Can also be used as a pure check.

unicode_requirements in includes/unicode.inc

Return Unicode library status and errors.

update_help in modules/update/update.module

Implementation of hook_help().

_update_cron_notify in modules/update/update.fetch.inc

Perform any notifications that should be done once cron fetches new data.

_update_requirement_check in modules/update/update.module

Private helper method to fill in the requirements array.