- CTDT_TABLE, /* Entire table. */
- CTDT_SUBTABLE, /* Innermost variable in a single layer. */
+ /* Within a section, where stacked variables divide one section from
+ another. */
+ CTDT_TABLE, /* All layers of a whole section. */
+ CTDT_LAYER, /* One layer within a section. */
+ CTDT_LAYERROW, /* Row in one layer within a section. */
+ CTDT_LAYERCOL, /* Column in one layer within a section. */
+
+ /* Within a subtable, where a subtable pairs an innermost row variable with
+ an innermost column variable within a single layer. */
+ CTDT_SUBTABLE, /* Whole subtable. */