[stringbuf.virtuals] balance parentheses in seekoff table

Author: jwakely

source/iostreams.tex

@@ -7664,8 +7664,8 @@
  positions the output sequence  \\ \rowsep
 \tcode{(which \& (ios_base::in |}\br
 \tcode{ios_base::out)) ==}\br
-\tcode{(ios_base::in) |}\br
-\tcode{ios_base::out))}\br
+\tcode{(ios_base::in |}\br
+\tcode{ios_base::out)}\br
 and \tcode{way ==} either\br
 \tcode{ios_base::beg} or\br
 \tcode{ios_base::end}     &