PARAMS_OPTIONAL
The configuration parameter PARAMS_OPTIONAL is one of four lists of compiler and linker options. PARAMS_OPTIONAL contains all options having one optional argument.
Example (for Microsoft's Visual C++ compiler cl)
PARAMS_OPTIONAL = /Fa,/FA,/Fd,/Fm,/Fr,/FR,/Gs,/Yc,/Yu,/YX,/Zp [...]