Character Set and Separators (GNAT Coding Style A Guide for GNAT Developers)

### 2.1 Character Set and Separators ¶

- The character set used should be plain 7-bit ASCII. The only separators allowed are space and the end-of-line sequence. No other control character or format effector (such as `HT`, `VT`, `FF` ) should be used. The normal end-of-line sequence is used, which may be `LF`, `CR/LF` or `CR`, depending on the host system. An optional `SUB` ( `16#1A#` ) may be present as the last character in the file on hosts using that character as file terminator.
- Files that are checked in or distributed should be in host format.
- A line should never be longer than 79 characters, not counting the line separator.
- Lines must not have trailing blanks.
- Indentation is 3 characters per level for `if` statements, loops, and `case` statements. For exact information on required spacing between lexical elements, see file style.adb.