commit not validated

Hi list,

I'd like to know if it is possible to commit code not updatable (not
validated) until a flag is set/unset ?

Here is our problem :
We have projects with source code and datas, and a buildmachine build
the executable(s).

At time 0 the code is commited, the buildmachine starts building.
At time + X (X >= 0) new data model is commited.
At time + Y (Y > X) compilation is successfull and the new data can be
read/write by the executable.

During time Y-X, the project is broken as the old executable can't read
new datas.
I wish to let people - data or source code providers - commit while they
cannot automatically update these revisions (they can force it, the
buildmachine for example needs new source code if something fails during
the previous build).

Something like "not validated" commits can be an answser, but I didn't
see anything allowing this on SVN.
I've thought to some other durty solutions, but I'd like to be sure
there's no clean way before starting anything.

-- 
Bastien Semene
Administrateur Réseau&  Système
Cyanide Studio - FRANCE