SQL puzzle

Here's a conundrum. Consider the following SQL statement:

select t1_key, t1_value, t1_foreign, t2_key, t2_value
  from table1 outer join table2
    on t1_foreign = t2_key
  order by t1_key;

If I read the SQL Reference (syntax diagram) correctly, this is wrong. It must be coded as LEFT OUTER JOIN, (or LEFT JOIN). And yet, my memory tells this has always been acceptable coding, with LEFT as the default. I fact, I tried it on V7.5 and V7.6 systems - and it works just fine

I also tried it on a V7.4 system - and it fails with:
SQL0199 Keyword OUTER not expected. Valid tokens: FOR USE SKIP WAIT WITH FETCH LIMIT ORDER UNION EXCEPT OFFSET.

So, my conundrums are:
1). It is OK to code OUTER JOIN, (and LEFT is assumed)?
2). Is there a PTF required on the V7.4 system - or are there problems on the V7.5 and V7.6 systems?
3). Is the SQL Reference incorrect?

(If anyone wishes to check this out I have a script I can paste here.)

TIA,
Brian.