Parameters don't work in FETCH NEXT clause?

A user of mine just raised a strange issue... While it is possible to use a
parameter in a LIMIT clause, PostgreSQL does not seem to allow using one in
a FETCH NEXT clause. In other words, while the following works:

SELECT 1 LIMIT $1;

The following generates a syntax error:

SELECT 1 FETCH NEXT $1 ROWS ONLY;

Since LIMIT and FETCH NEXT are supposed to be equivalent this behavior is
odd.

More generally, is there some documentation on where exactly PostgreSQL
allows parameters and where it doesn't? I occasionally get complaints from
users expecting parameters to work in DDL, or even in table/column names in
SELECT queries... I haven't seen a resource like this.