Server side large object functions

Hi,

The PostgreSQL manual indicates that:

"There are server-side functions callable from SQL that correspond to each
of the client-side functions described above."

In psql I can get the argument data types for lo_open:

development=# \df+ lo_open
List of functions
Schema | Name | Result data type | Argument data types | Volatility
| O
wner | Language | Source code | Description
------------+---------+------------------+---------------------+------------+---
-------+----------+-------------+-------------------
pg_catalog | lo_open | integer | oid, integer | volatile
| po
stgres | internal | lo_open | large object open
(1 row)

But if I try to find the same for lo_read I get:

development=# \df+ lo_read
List of functions
Schema | Name | Result data type | Argument data types | Volatility | Owner
| L
anguage | Source code | Description
--------+------+------------------+---------------------+------------+-------+--
--------+-------------+-------------
(0 rows)

Is there not a server side function for lo_read? If so, how do I determine
the argument types?

My objective it to read a large object into memory as opposed to exporting
it to a disk file.

I'm using version 8.3.3, psqlODBC 8.2.2 and vb.net.

Thanks,
George