[Proj] Geodetic datum for the "Netherlands East Indies Southern Zone"?

[Mikael Rittri]

Hello all,

I have come across an Indonesian map. In the legend, it says 
that the ellipsoid is Bessel and the projection is Lambert Conic
Orthomorphic. The projection parameters agree with the "Netherlands
East Indies Southern Zone", covering Java and the Lesser Sunda Islands,
as described by Clifford Mugnier in his column on Indonesia (page 1160,
left column).
http://www.asprs.org/a/resources/grids/10-2009-indonesia.pdf

The projection is not listed in the EPSG database, as far as I can see.

What I am not sure of, is the geodetic datum. The graticule of the 
map showed longitudes from Jakarta, but that doesn't help much, since
many local geodetic datums in Indonesia use Jakarta as the prime meridian.

In the EPSG database, the only geodetic datums that fit - using the
Bessel ellipsoid and covering Java - are Batavia and Batavia (Jakarta),
EPSG codes 6211 and 6813. And I noticed that the "Netherlands East
Indies Equatorial Zone", also mentioned by Mugnier, is listed in 
EPSG (code 3001), and uses the Batavia datum. 

Can I conclude that the Netherlands East Indies Southern Zone also
uses the Batavia datum, or could it use some other datum that is
not listed by EPSG? 

Regards,

Mikael Rittri
Carmenta
Sweden
http://www.carmenta.com