[EDIT: In my original post, I had received an error that was based on a typo, so I scrapped that part of the question, but left the questions that still apply.]
In the ogr2ogr docs it says:
-nlt type: Define the geometry type for the created layer. One of NONE, GEOMETRY, POINT, LINESTRING, POLYGON, GEOMETRYCOLLECTION, MULTIPOINT, MULTIPOLYGON or MULTILINESTRING. Add "25D" to the name to get 2.5D versions.
Does this part:
Add "25D" to the name to get 2.5D versions apply to both loading things into postgres as well as exporting data from postgres to .shp files?
Additionally, I am assuming 25D to meant that one can have a z value that corresponds to each pair of xy coordinates (as is the case with PolygonZ shapefile types), but that these coordinates may not overlap. Is this correct? What is the intended distinction in this case between 2.5D and 3D?