Portuguese non-headed sentences - again

[José Catarino (by wayofJosé Catarino <jose.catarino@mail.telepac.pt> by way of José Catarino <jose.catarino@mail.telepac.pt>)]

I want to thank all the responses I received. They are an important
contribution to the study of the problem.
I would like to explain just a few things:
1. I use the expression "context-free " to say that these expressions are
independent of the context. I was not speaking of "context-free grammar's".
2. I am studding the suggested bibliography, specially Bender (2000) and De
Kuthy (2000). The sentences that I speak of seems to me a very different
problem.
3. I want to thank Detmar's suggestions, which are important
methodological orientation.
4. Wesley Davidson pose some interesting questions. The answer is "yes",
these expressions can "occur as the complement of verbs that select
sentential complements":
a. O Pedro diz [que só chove sábado].
'Peter says that it rains only Saturday'
b. O Pedro diz [que chuva, só sábado].
'Peter says that rain only Saturday'
For the moment, I am working in the restrictions that allow these
expressions, which are not described - as far as I know of- in the
Portuguese's grammars.
If somebody has other suggestions, I would be gratefull.
José Catarino