--enable/disable-mathmldtd autogen option

I noticed that the default state of the --enable-mathmldtd option is
*off*, but the help text suggests it is *on* by default:

  --disable-mathmldtd     Disable mathmldtd (useful for distributions that
                          want to avoid packaging it).

In the process of correcting that, I thought it deserved a better help
text, so I looked at what this option does, and I noticed:

1) None of distro-configs/* enable it

2) I'm not sure it does much, because:

$ git grep -A10 -B5 MATHMLDTD
configure.in-dnl
===================================================================
configure.in-AC_MSG_CHECKING([whether to include MathMLDTD])
configure.in-if test -n "$enable_mathmldtd"; then
configure.in-    if test "$enable_mathmldtd" = "no"; then
configure.in-        AC_MSG_RESULT([no])
configure.in:        SCPDEFS="$SCPDEFS -DWITHOUT_MATHMLDTD"
configure.in-    else
configure.in-        AC_MSG_RESULT([yes])
configure.in:        BUILD_TYPE="$BUILD_TYPE MATHMLDTD"
configure.in-    fi
configure.in-else
configure.in-    AC_MSG_RESULT([no])
configure.in:    SCPDEFS="$SCPDEFS -DWITHOUT_MATHMLDTD"
configure.in-fi
--
scp2/source/math/file_math.scp:#ifndef WITHOUT_MATHMLDTD
scp2/source/math/file_math.scp-File gid_File_Html_W3c_Ipr
scp2/source/math/file_math.scp-    TXT_FILE_BODY;
scp2/source/math/file_math.scp-    Styles = (PACKED);
scp2/source/math/file_math.scp-    Dir = gid_Dir_Share_Dtd_Math_1_01;
scp2/source/math/file_math.scp-    Name = "w3c_ipr_software_notice.html";
scp2/source/math/file_math.scp-End
scp2/source/math/file_math.scp-
scp2/source/math/file_math.scp-#endif


So it like it *only* installs the file w3c_ipr_software_notice.html,
and not the file MathMLDTD/math.dtd, like it looks like it is supposed
to.

Or I misunderstand how our install/packaging process works: I assume
Dir = "gid_Dir_Share_Dtd_Math_1_01" only creates the directory, not
installs its whole contents that is populated by Makefiles.

In the other case, maybe this is a duplicate because
MathMLDTD/Package_bin.mk has:

$(eval $(call gb_Package_add_file,MathMLDTD_bin,bin/math.dtd,math.dtd))
$(eval $(call 
gb_Package_add_file,MathMLDTD_bin,bin/w3c_ipr_software_notice.html,w3c_ipr_software_notice.html))

which looks like it would install both or none.


3) If this all works, it installs --- eeeek!! ---- a *modified* MathML
   DTD. So either we need the modified DTD and this should be enabled
   by default, or we don't need the modified DTD (we are OK with the
   pristine W3C DTD) and then why optionally install a modified one?
   We should *maybe* optionally install the *pristine* one. I can
   imagine we'd like to bundle it at least on platforms where it is
   not already available?

   Anybody has any info on that?

-- 
Lionel