-/* Copy SOURCE to DEST, escaping non-printable characters. If FOR_URI
- is 0, they are escaped as \ooo; otherwise, they are escaped as
- %xx.
+/* Copy SOURCE to DEST, escaping non-printable characters.
+
+ Non-printable refers to anything outside the non-control ASCII
+ range (32-126) which means that, for example, CR, LF, and TAB are
+ considered non-printable along with ESC and other control chars.
+ This is by design: it makes sure that messages from remote servers
+ cannot be used to deceive the users by mimicking Wget's output.
+ Disallowing non-ASCII characters is another necessary security
+ measure, which makes sure that remote servers cannot garble the
+ screen or guess the local charset and perform homographic attacks.
+
+ Of course, the above means that escnonprint must only be used in
+ decidedly ASCII-only context, such as when printing host names,
+ responses from HTTP headers, messages coming from FTP servers, and
+ the like.
+
+ ESCAPE is the character used to introduce the escape sequence.
+ BASE should be the base of the escape sequence, and must be either
+ 8 for octal or 16 for hex.