# 65.5. Examples

The PostgreSQL source distribution includes several examples of index operator classes for SP-GiST, as described in [Table 63.1](https://www.postgresql.org/docs/10/static/spgist-builtin-opclasses.html#SPGIST-BUILTIN-OPCLASSES-TABLE). Look into `src/backend/access/spgist/` and `src/backend/utils/adt/` to see the code.