Combining several CTEs with a recursive CTE

Hello all,

this is more a "just curious" question, rather than a real world problem.

We can combine several CTEs into a single select using something like this:

WITH cte_1 as (
select ....
),
cte_2 as (
select ...
where id (select some_col from cte_1)
)
select *
from cte_2;

But this does not seem to work when a recursive CTE is involved

WITH cte_1 as (
select ....
),
recursive cte_2 as (
select ...
where id (select some_col from cte_1)

union all

select ...
)
select *
from cte_2;

This throws an error: syntax error at or near "cte_2"

I'm just wondering if this is intended behavioury, simply not (yet) implemented or even invalid according to the standard? I didn't find any reference that it's not allowed in the manual.

Regards
Thomas