The present invention provides methods for exposing an avian embryo to light during incubation. For example, portions of a data block can be read separately for each on-track and off-track position in the data block; then, the separately read portions can be recombined into a recovered data block. The calibration includes a substantially sealed volume of fluid in fluid communication with the test arrangement and a control arrangement for heating andor cooling the volume to produce the source of the calibrator. The stand includes a first supporting piece and a second supporting piece obtusely connected to the first supporting piece. The latching logic controls the state of a latch node based on the state of the pre-charged node during an-evaluation period between a first edge of said clock signal and a second edge of the clock signal. A and B may be the same or different.