It is essentially raw text just like the words you are reading now. Each byte in the file contains one character that conforms to the standard ASCII code (see ASCII chart). Program source code ...

The sequential order of ASCII data. In ASCII code, lower case characters follow upper case. True ASCII order would put the words DATA, data and SYSTEM into the following sequence. See ASCII chart.

Not exactly schematics, but [Duckman] has some Arduino pinout diagrams he made using ASCII-art. These could be useful when pasted into source code as comments, documenting the pinouts for your ...