Yes it is correct
query1=(db.table.field==value)|(db.table.field==other_value) is a SQLQuery
db(query1) is a SQLSet
db(query1)(query2) is a subset, the same as set defined by
db((query1)&(query2))
They are equivalent notations.
In a SQLSet you can:
db(query1).select(db.table.field)db(query1).delete()db(query1).update(field=value)