+When @code{YYLTYPE} is not defined, at the beginning of the parsing, Bison
+initializes all these fields to 1 for @code{yylloc}. To initialize
+@code{yylloc} with a custom location type (or to chose a different
+initialization), use the @code{%initial-action} directive. @xref{Initial
+Action Decl, , Performing Actions before Parsing}.