check_markup in core/modules/filter/filter.module
Runs all the enabled filters on a piece of text.
system_update_1057 in core/modules/system/system.install
Add default for watchdog_enabled_severity_levels.
watchdog_severity_enabled in core/includes/bootstrap.inc
Check if logging is enabled for a given severity level.
watchdog_severity_levels in core/includes/common.inc
Returns a list of severity levels, as defined in RFC 3164.