Is 1.5 dCi based on Delphi servo-solenoid balanced valve?

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Copy and paste the following from :

Delphi Enters High Volume Production With the World's First Diesel Fuel Injection System to Use Revolutionary Direct Acting Piezo Injectors

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Therefore, the different types of injectors existing so far were:

--  servo-solenoid unbalanced valve (first Common Rail type introduced in
the market);
--  servo-solenoid balanced valve (Delphi's concept in production)
--  servo-piezo unbalanced valve (only type of piezo injector in
production to date);
--  (There is no servo piezo balanced valve design currently in
production).

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Does this mean that Renault 1.5dCi diesel engine is based on "servo-solenoid
balanced valve"?

Have yet to find out any info on this "balanced valve" and "unbalanced valve".
What does it mean by balanced and unbalanced?