<?php

// APPROACH A: One magical entity

// CRUD for domain-level settings
civicrm_api('Setting','create', array(
  'id' => $ // optional if single-domain; mandatory for multiple domain
  'timezone' => $,
));
// CRUD for contact-level settings
civicrm_api('Setting','create', array(
  'contact_id' => $ // optional; default current user
  'timezone' => $,
));
// R for settings
civicrm_api('Setting', 'resolve', array(
  return => 'timezone',
));

// APPROACH B: Three (somewhat) magical entities

// CRUD for domain-level settings
civicrm_api('DomainSetting','create', array(
  'id' => $ // domain id; optional if single-domain; mandatory for multiple domain
  'timezone' => $,
));
// CRUD for contact-level settings
civicrm_api('ContactSetting','create', array(
  'id' => $ // contact id; optional; default current user
  'timezone' => $,
));
// R for settings
civicrm_api('Setting', 'get', array(
  return => 'timezone',
));