One example to build a library is a classified as a rare-cutting restriction endonuclease such as NotI.  In order to construct and characterize a library based from NotI-digested human DNA, random clones were analyzed by restriction mapping. Due to the wide distribution of fragment sizes made by the complete digestion with NotI, the library was constructed into two fractions, low and high plasmid concentration. Clones that possessed unique end fragments were then analyzed by hybridization to Pulse Field Gradient (PFG) Southern blots. Examining the results gathered for single and double digests of human DNA with enzymes NotI, BssHII, and NruI, a restriction map with 850 kb was region containing the linking and jumping clones were created. Furthermore, NotI fragments of 250 and 350 kb jumps were evident in the two end clones derived corresponding to  genetic distances of 0.25 and 0.35 cM.