While reading about the place and sources of contract law, I was surprised about the fact, that only the German BGB has a elaborate structure.
The German BGB is split into 5 Books. Every Book is split in several Sections with several Titles. Maybe the most important book is the first Book, named the General Part. It contains regulations applying to the whole BGB. It has a very high grade of abstraction. You can say the General Part of the BGB are regulations "placed outside the bracket".
E.g. Section 1 treats with persons. It defines in Title 1 Natural Persons, so in § 13 and §14 consumer and entrepreneur. Title 2 is about Legal persons. These definitions universally valid in the whole BGB and e.g in the Commercial Code concerning the definitions of Legal Persons. Thus it is a big advantage. The second big advantage is the fact, all these definitions are codificated in one book, you can always take with you. You don't to know or to search for cases which could fit to the problem like in English Common law.
But when we take a more detailed look on the General Part of the German BGB we notice that it would incompatible for a common European Private law, because the General Part of the BGB is remarkable for its high grad of abstraction and its tight relation to the German language. A lot of German jurists struggle with understanding and interpreting the General Part and the translation of those abstract formulations into the 23 languages of the European Union would be more than difficult.
A compromise between the very abstract General Part of the BGBn in Germany, the very clear commentary stile of the French Code Civil and the enourmous and complicated English Common Law might be the solution choosen by the drafters of the Draft Common Frame of Reference, a model of a European Private Law codification. The DCFR consists of General Provisions which are comprehensible for everyone and not only for the educated jurist with good interpretation skills.
Beale, Fauvarque-Cosson, Rutgers, Tallon, Vogenauer : Ius Commune Casebooks for the common Law of Europe, Cases, Materials and Text on Contract Law