Inverse Linkage Oligonucleotides ("ILO") useful in enzymatic process are disclosed. Particularly preferred ILOs are amenable to enzymatic elongation from either, or most preferably, both termini. In a particularly preferred embodiment, each terminus of an ILO has an enzymatically functional 3' group. Accordingly, under appropriate conditions and in the presence of, e.g., dNTPs, enzyme, sample DNA, and ILO comprising a first region complementary to a first region of the sample DNA and a second region complementary to a second, different region of the sample DNA, exponential amplification of the sample DNA can be effectuated.