character sequence

A character sequences matches text a character at a time, exactly as
if each character had been specified separately in a sequence.  This
allows whitespace to be skipped between the characters of a literal,
provided that a %whitespace directive is in effect.

A character sequence is written like `%c"..."` or %c'...'`.  The "c"
stands for "characters."

The character sequence:

    %c"THEN"

is equivalent to

    ("T" "H" "E" "N")

Most of the time, you probably want a string literal.  Character
sequence exists for strange languages like BASIC and Fortran, which
permit whitespace in keywords.