About the macro defined in Rinternals.h

Hello everyone,

I try to  write a c++ code which calls embedded R and uses some of R 
internal functions. What I read is just lots of macro names defined in 
the Rinternals.h or Rdefines like R_Parse, Rf_install and so on. But 
where can I get the detailed information about the parameters of these 
macro?  For example, what about the parameters of  SEXP 
R_ParseVector(SEXP, int, ParseStatus *)?

Thank you very much!

Baiyi Song
Computer Engineering Institute
Dortmund Univercity