159   if (const std::optional<std::string> charConst{GetConstExpr<std::string>(  in Enter()  local
161     std::string s{Normalize(*charConst)};  in Enter()
167     CheckStringValue(specKind, *charConst, parser::FindSourceLocation(spec));  in Enter()
173           *charConst);  in Enter()
493   if (const std::optional<std::string> charConst{  in Enter()  local
495     flags_.set(Flag::AsynchronousYes, Normalize(*charConst) == "YES");  in Enter()
496     CheckStringValue(IoSpecKind::Asynchronous, *charConst,  in Enter()
528   if (const std::optional<std::string> charConst{GetConstExpr<std::string>(  in Enter()  local
531       flags_.set(Flag::AdvanceYes, Normalize(*charConst) == "YES");  in Enter()
533     CheckStringValue(specKind, *charConst, parser::FindSourceLocation(spec));  in Enter()
607   if (const std::optional<std::string> charConst{  in Enter()  local
610     std::string s{Normalize(*charConst)};  in Enter()
618           IoSpecKind::Status, *charConst, parser::FindSourceLocation(spec));  in Enter()
624           "Invalid STATUS value '%s'"_err_en_US, *charConst);  in Enter()