The special comments that make up Foundation Express compiler directives begin, like all Verilog comments, with the characters // or /*. The // characters begin a comment that fits on one line (most Foundation Express compiler directives fit on one line). If you use the /* characters to begin a multiline comment, you must end the comment with */. You do not need to use the /* characters at the beginning of each line, only at the beginning of the first line. The word synopsys (all lowercase) following the comment characters tells Foundation Express to treat the text following the word synopsys as a compiler directive.
You cannot use // synopsys in a regular comment. In addition, the compiler displays a syntax error if Verilog code is in a
// synopsys directive.
