Catalan Opening for White repertoire, analysed in detail. This first volume (of two), after the opening moves 1.d4 d5 2.c4 e6 3.Nf3 Nf6 4.g3, is devoted to the so-called Open Variation, where Black continues with 4..dxc4. Also discussed are all the lesser played continuations in Black's 4th move (4..Bd6, 4..c5). The so-called Closed variation, where Black does not take on c4 and continues 4..Be7 or 4..Bb4+, will be discussed in the second part. Further information about the book and a sample are available at thinkerspublishing.com. 2 pictures.