Let me explain with example... Consider 'android.R.layout.simple_list_item_multiple_choice'. It used to create multi-select lists. But the only definitions I found:
/platform/frameworks/base/core/res/res/values/public.xml:
<public type="layout" name="simple_list_item_multiple_choice" id="0x01090010" />
/platform/frameworks/base/api/current.xml:
<field name="simple_list_item_multiple_choice"
type="int"
transient="false"
volatile="false"
value="17367056"
static="true"
final="true"
deprecated="not deprecated"
visibility="public"
>
But where is actual layout defined? When multi-select list created I see checkbox, where it comes from?