Contains low-level machine code and addresses of a compiled C or Assembly program; saved in a text format that represents hexadecimal coded binary data; used by the Freescale series of microcontrollers. Each line in an S19 file consists of one record. Every record begins with the letter "S," followed by a "1" if the record contains data or a "9" if it is the last record in the file.
File extension S19 is indeed a Motorola hex file extension used by their programmers (electronic programmers not people) to program microcontrollers that had EPROM on board. It is actually a text file that contains the hex code for the controller targeted.