Abstract: The idea of this invention is to prepare ordered oligonucleotides arrays from two or more pre-synthesized shorter parts—block-synthesis approach. The parts are linked together enzymatically to form a full-length oligonucleotide of a desired sequence. Such an approach allows splitting the oligonucleotide sequences into common and unique parts. It gives the possibility to place the functional group on a common part and to minimize the length of the unique parts. Method of the invention allows combinatorial synthesis of position-specific regions. Using combinatorial approach, position-specific regions are generated by linking two or more unique oligonucleotides, so that just few said unique oligonucleotides give rise to a large variety of codes, for example, 10 unique oligonucleotides linked pairwise can produce 100 position-specific regions.