why is the name `loop` treated differently in PostgreSQL

I issue the following DDL:

CREATE TABLE foo
(
loopa INTEGER,
loop  INTEGER
);

Then, examining the DDL in the server (using a client-side tool like DbVisualizer - sorry don't know the query to produce it directly) I see the following:

CREATE TABLE
    foo
    (
        loopa INTEGER,
        LOOP INTEGER
    );

Observe the change in case for the column named loop but not for the one named loopa. Looking at the list of SQL keywords loop doesn't appear to be a keyword. Why then, this selective change?

This seems to be related to a problem I am having with a trigger trying to access a column loop in a table where I get:

Exception in thread "main" org.postgresql.util.PSQLException: ERROR: record "new" has no field "loop"

(where I get the same error regardless of whether the code in the trigger function access the field as NEW.LOOP or NEW.loop)

UPDATE

The upper-casing seems to be an artifact of DbVisualizer. psql shows:

psql (9.1.13)
Type "help" for help.

foo-test=> \dS+ foo
                    Table "test.foo"
 Column |  Type   | Modifiers | Storage | Description 
--------+---------+-----------+---------+-------------
 loopa  | integer |           | plain   | 
 loop   | integer |           | plain   | 
Has OIDs: no

Yet this still doesn't explain why the PostgreSQL engine apparently doesn't allow my trigger to access NEW.loop. When I rename the column (and the trigger code) to loopi everything appears to work fine. So, there is likely something deeper at work here than just a DbVisualizer glitch. I'll try to create a SSCCE later.

UPDATE 2

A SSCCE for the trigger problem has been created here.