FIGURE 16.1 - Labeling microtiter plates. Each plate should be labeled with information regarding its contents and origin. Traditionally each label is placed on the "frosted" end of the plate. Labels should be uniform in format. In the example above, the species (S. bicolor = Sorghum bicolor), the cultivar/genotype (BTx623), and the date that the library was made (09/99 = September 1999) are listed on the horizontal surface of the label. Copy information (Master Copy), a "quality" designation (QI), and the plate number (Plate 112) are given on the vertical surface of the label. The "quality" (Q) of the copy is based upon how far removed it is from the master copy. For example, the master copy itself has the highest quality and is given the designation QI. A library generated using the master copy as a template would be labeled QII (usually Copy 1 and Copy 2 of the library are directly made from the master copy). A copy made from a QII library would be labeled QIII, etc.