The INFO directory, %library_location%/INFO, contains two files: LAYERS and INDEX.PAT. The LAYERS file has two items NAME and COVERAGE. NAME contains the layer's name and COVERAGE contains the map section name.
Use the ArcPlot RESELECT INFO command on the LAYERS file to reselect the layer. Then use the AML functions [EXTRACT] and [SHOW SELECT] to move the map section name into an AML variable.
Next determine the path to a tile containing a map section. Tiles lacking data for the layer, also lack a map section. The layer item in the INDEX.PAT is coded 'P' when a map section is present in the tile. The INDEX.PAT item LOCATION is coded with the path to each tile directory. The ArcPlot RESELECT command can be used to select tiles with data. [SHOW SELECT] can be used to reduce the reselected tiles to just one. Use the AML functions [EXTRACT] and [SHOW SELECT] to move the path of the one reselected tile into another AML variable. Next, do an AML &DESCRIBE on the map section.