Fields of Anthropology. There are now four major fields of anthropology: biological anthropology, cultural anthropology, linguistic anthropology, and archaeology. Each focuses on a different set of research interests and generally uses different research techniques.
SPC is one of the three categories of Statistical Quality Control (SQC). SQC is a statistical method of analyzing variations in the manufacturing process in order to make it better and more effective. Only a certain number of samples are needed to determine whether the products are acceptable.
The Network Access Code or NAC is a feature of Project 25 digital radios similar to CTCSS or DCS for analog radios. That is, radios can be programmed to only break squelch when receiving the correct NAC. NACs are programmed as a 3 digit hexadecimal code that is broadcast along with the digital signal being transmitted.