"1" & "2" were used in v5.0: before the search views existed, the tree views had search filters on the "select=1" fields, and additional others hidden behind an "extended search" button (the "select=2" fields).

Looks like the docs are outdated.

Now select can be False(default) and True.

In OpenERP v6.x:

• If you define in ORM (*.py) select=True, then create index in DB for search optimization and insert in default search view.

• If you define in XML select=True, then field insert in default search view.

In OpenERP v7.x:

• If you define in ORM (*.py) select=True, then create index in DB for search optimization.

• If you define in XML select=True, then no effect.