Geographic Information System (GIS) Question:

► What are the United States map accuracy standards?
► What is the Vector Product Format and where can I get information?
► What is this SDTS thing and is it available via ftp?
► What is a DXF file and where can I get info about it?
► What is DEM and where can I find out about some?
► Where can I get information about TIGER/Line?
► How do I order USGS maps?