281 
GLSS currently operates on a five-digit (tag) code interactively assigned by the 
AGDS operator to each chart feature line segment. To support ATM 
symbolization requirements, the four least significant digits are interpreted by 
GLSS for generation of the symbology, while the most significant digit is used 
to indicate the direction of ticking (depressions, fills, cuts, etc.) as required by 
the chart specifications. GLSS codes currently defined to support ATM 
production are basically separation oriented (Table 4). Exceptions will occur. 
Table 4. ATM Symbology 
GLSS Code 
Separation 
// Symbols 
OXXX 
Cultural Features 
32 
1XXX 
Roads, Railroads 
43 
2XXX 
Boundaries 
12 
3XXX 
Coastal Hydrography 
19 
4XXX 
Hydrography 
67 
5XXX 
Hypsography 
37 
7XXX 
Vegetation 
4 
8XXX 
Aeronautical 
21 
9XXX 
Launch sites, isogonics 
6 
The majority of these codes was generated from the "Defense Mapping Agency 
Standard cartographic Feature Digital-Identification Catalog" and currently 
utilizes all four digits (e.g., 4001-swamp, 4601-well, 0156-aerial cableway, 
etc.). An analysis of Table 4 and current ATM symbolization requirements 
indicates that Hydrography has the largest (67) symbolization requirements. 
DMAAC is investigating the feasibility for a logical reordering of the GLSS tag 
assignments. Current requirements could be supported by just two digits, 
allowing the least significant digit available to yield another level of filtration. 
Production procedures will be developed to allow a cartographer, versed in 
multi-series feature portrayal and specifications requirements, to tag each 
feature segment according to the subsequent product scale chart (Fig. 5) it 
could support. For purposes of demonstration, assume 1:200,000 (ATM) to be 
the source generation scale for insertion into DCAD. Assume also that after 
several scale changes, feature thinning and generalization would be required. 
Thus, to filter drainage to support a 1:1,000,000 scale series chart, all segments 
tagged with less than a 4 in the least significant digit (Table 5) would not be 
selected. Furthermore, all least significant digits over 2 would require thinning 
and generalization. For this to work, the source scale would have to be 
standard for DCAD and each smaller scale product code would have to be 
ordered by scale. 
Table 5. FOC Filtering 
CHART SCALE 
GLSS 
1:200,000 
4XX1 
1:250,000 
4XX2 
1:500,000 
4XX3 
1:1,000,000 
4XX4