What does read-char get at the end of a line?

[ramsdell@linus.mitre.org]

Is it specified that read-char of a port at the end of a line returns
exactly one character, and that character is #\newline?  If it is not
true, how do I write portable code that reads a file one character at
a time?  If it is true, please give me a reference to the relevant
section in R3.99RS.

John

PS.  Suppose I would like to write my own reader in Scheme that
includes syntax in which #\; is treated as end of file.  When my
reader gets #\;, what portable Scheme expression should be used to
return an object to which eof-object? answers true?