| Subject | English | Bulgarian |
| comp., MS | physical layer | физически слой (Layer one of the OSI model. A software layer that transmits bits from one computer to another and regulates the transmission of a stream of bits over a physical medium. This layer defines how the cable is attached to the network and which transmission technique is used to send data over the cable) |
| transp., avia. | physical layer protocol data unit | протоколен блок данни от физически слой |