In the circuit description, an asterisk (`*') as the first non-white space character indicates that this line is a comment line. Also, if the sequence ` \$' appears in a line of input and is preceded by white space or is at the beginning of the line, the characters that follow are ignored. Comments may be placed anywhere in the circuit description.
Comment lines which begin with `*@' and `*#' in the circuit description are special: they are taken as executable statements as if included in .exec or .control blocks, respectively (see 2.10.1).
In .exec and .control blocks, comments are indicated for lines with the first non-whitespace character being `#', for compatibility with the shell. In Verilog blocks, The C++ commenting style (``//'' for single line comments and ``/* ... */'' for multi-line comments) is recognized.