General :: Read Default System Settings

Context: Today im investigating how works android classes:

android.provider.Settings.Secure and android.provider.Settings.System

both works over settings.db into

data/data/com.google.android.providers.settings/databases/settings.db.

There is something that surprised me:

When I had never changed one of settings, for example LOCK_PATTERN_ENABLED, the method:

getString(ContentResolver resolver, String name) returned null.

By default lock pattern is disabled when i activated it, method returned 1 and then when disabled returned 0.

My question: is true that when you havent changed the value of a setting, the system goes to look for its default value out of settings.db? and is true that this value at settings.db until you change it is null?

I've read some post about it, but no one working against api. For who may be interested: [URL] .......

I decompiled Settings.apk, SettingsProvider.apk and Phone.apk. There you can find some bools.xml where are stablished default values for some settings I've not found yet every setting I need.