Tile a11g was posted on 30 May 2000 with the following three enhancements over tile a10g:

1. In the area between 66 and 67 degrees north latitude, 162 and 165 degrees west longitude:
   The data were discovered to be low by a ratio of feet to meters.  This suggests that the
   original Defense Mapping Agency data, reformatted and distributed by the U. S. Geological
   Survey (GLOBE data type 5) were erroneously divided by that ratio.  The source 3 arc-second
   data were multiplied by 3.28, compared with Digital Terrain Elevation Data for confirmation,
   then substituted at these new values into tile A.

   In source/lineage tile a11s, corresponding to this data tile a11g, areas so changed were 
   given a source/lineage category 51.  This class is considered original source 5, modified
   by NGDC for GLOBE update version 1.1 for this tile.  At the time of this work, other DEMs
   still apparently use the erroneously vertically referenced category 5 data in this area.

2. In the area between 61 and 62 degrees north latitude, 162 and 163 degrees west longitude:
   The source 3 arc-second USGS tile was found to cover only the northern half of this 1-degree
   area.  The 3 arc-second data (GLOBE data type 5) were resampled to 30", and combined with
   DTED level 1 discrete data (GLOBE data type 1) covering the southern half of the area.
   The resultant tile was compared with Digital Terrain Elevation Data for confirmation, 
   then substituted into tile A.

   In source/lineage tile a11s, corresponding to this data tile a11g, areas so changed were
   given a source/lineage category 51.  This class is considered original source 5, modified
   by NGDC for GLOBE update version 1.1 for this tile. Note that some of the updating uses
   GLOBE source/lineage category 1 data to replace nonexistant (previously misplaced) 
   source/lineage category 5 data.  At the time of this work, other DEMs still apparently
   use the misplaced category 5 data in their compilations. 

3. In the area between 69 and 69 degrees north latitude, 134 and 135 degrees west longitude:
   The lowest-lying part of the Mackenzie River delta was labelled 15 meters, whereas the
   majority of that part of the delta (e.g. immediately to the west and south) was labelled
   1 meter elevation.  Many such modest discontinuities are found between 1x1 degree DTED
   cells.  In this case, however, visualizations of the data were adversely affected.  So
   that part of the delta in the abovementioned area was relabeled to 1 meter elevation, to
   be consistent with the data for the rest of the delta.

   In the source/lineage tile a11s, corresponding to this data tile a11g, areas so changed were
   given a source/lineage category 3a.  This class is consisered original source 3, modified
   by NGDC for GLOBE update version 1.1 for this tile.  At the time of this work, other DEMs
   still apparently use the discontinuous category 3 data in their compilations.

This work was assisted by Sven Trudeau, of the Ecole Superieure des Geometres et Topographes (ESGT),
Le Mans, France, during his visit to NGDC during January-July 2000, working on GLOBE.