Creates a special-comment value that encapsulates v. The read, read-syntax, etc., procedures treat values constructed with make-special-comment as delimiting whitespace when returned by a reader-extension procedure (see Reader-Extension Procedures).

Returns #t if v is the result of make-special-comment, #f otherwise.

Returns the value encapsulated by the special-comment value sc. This value is never used directly by a reader, but it might be used by the context of a read-char-or-special, etc., call that detects a special comment.