Apparently older versions of makeinfo insist on this.
Reported-by: Harry Thijssen
Fix-by: Ben Pfaff
If specified, @subcmd{MATRIX IN} must be followed by @samp{COV} or @samp{CORR},
then by @samp{=} and @var{file_spec} all in parentheses.
@var{file_spec} may either be an asterisk, which indicates the currently loaded
-dataset, or it may be a filename to be loaded. @xref{MATRIX DATA} for the expected
+dataset, or it may be a filename to be loaded. @xref{MATRIX DATA}, for the expected
format of the file.
The @subcmd{/EXTRACTION} subcommand is used to specify the way in which factors (components) are extracted from the data.