Explain config_type_extended usage and purpose
From legacy/trac#31494 (moved), previously from legacy/trac#30914 (moved):
Make sure that we have a good explanation of CONFIG_TYPE_EXTENDED, how it is used, and how it relates to the type_def pointer.
From legacy/trac#31494 (moved), previously from legacy/trac#30914 (moved):
Make sure that we have a good explanation of CONFIG_TYPE_EXTENDED, how it is used, and how it relates to the type_def pointer.