Types of blocks in the `pg_stat_statements`

I cannot get understanding about what different types of blocks means here:
http://www.postgresql.org/docs/current/interactive/pgstatstatements.html

I assume, that `shared` are blocks from the `shared_buffers`

and `temp` are blocks used by temporary files (absence of `dirtied` and `hit` also speaks for this).

But what `local` blocks mean?

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