When reading input TeX converts the sequences of read characters into
a sequence of tokens. When TeX sees a backslash \
, it
will handle the following characters in a special way in order to make a
control sequence token.
The control sequences fall into two categories:
\
followed by at least one ASCII letter, followed by at least one
blank. The sequence of at least one ASCII letter is called the
control sequence name.
\
followed by one non-letter character.
Blanks after a control word are ignored and do not produce any
whitespace in the output (see \newcommand
& \renewcommand
and
Backslash-space, \
).
Just as the \relax
command does nothing, the following will print
‘Hello!’:
Hel\relax lo!
This is because blanks after \relax
, including the newline are
ignored, and blanks at the beginning of a line are also ignored
(see Leading blanks).