Below is a list of files and a brief description of what they contain:

dsnSeedE.A     - This is a MicroStation seed file that is used for A sheets.
                 The first A sheet will consist of a title sheet. The second
                 sheet will be used as a legend of symbols contained in the
                 plan, including utility information. The third sheet can be
                 used for a detailed project map, if required, and the last
                 sheet will contain revision information if needed 

dsnSeedE.B     - This is a MicroStation seed file that is used for B (Typical)
                 and C (Tabulation) sheets. There are 20 sheet borders within
                 this file, and all of them may be used if up to 20 B or C
                 sheets are needed for a project

dsnSeedE.G     - This is a MicroStation seed file that is used for G sheets
                 (Benchmarks and Reference Ties). There are 20 sheet borders
                 within this file, and all of them may be used if up to 20 G
                 sheets are needed for a project

dsnSeedE.L     - This is a MicroStation seed file that is used for L Sheets
                 (Intersection). It is a 20 scale file, and there are 4 sheet
                 borders within this file. They are usually used for a single
                 intersection to represent up to four different sheets. The
                 information contained on these sheets is the intersection
                 geometrics, the intersection staking, the intersection
                 jointing, and the intersection edge profiles

dsnSeedE.Mass  - These files are all used as part of the Earthwork process
                 developed by the IDOT. The MicroStation file dsnSeedE.Mass
                 is a seed file that references the original file dsnOrigE.Mass,
                 which is the grid upon which the Mass Diagram is drawn. The
                 last piece is the Mass2000a.exe program, which is a Visual
                 Basic program that uses Geopak Earthwork runs to create the
                 Mass Diagram information which is plotted into the MicroStation
                 sheets which were previously mentioned

dsnSeedE.Q10   - These are MicroStation seed files that are used for Q sheets 
dsnSeedE.Q100    (Soils). There are four different scales (100, 50, 20, and 10),
dsnSeedE.Q20     and each file contains a single sheet, usually in a plan /
dsnSeedE.Q50     profile layout. These sheets contain soils boring information
                 and soils layer lines

dsnSeedE.T1    - These are MicroStation seed files that are used for T sheets 
dsnSeedE.T2      (Earthwork). Each file contains 4 sheets, and they are set up
                 to work in conjunction with the Geopak Earthwork files that can
                 be downloaded on the Geopak page of this website

dsnSeedE.U     - This is a MicroStation seed file that is used for U sheets
                 (Design Details). There are 20 sheet borders within this file,
                 and all of them may be used if up to 20 U sheets are needed for
                 a project. This seed file also has 20 IDOT logos that are
                 referenced to the sheet borders to compliment the Design Detail
                 Sheets

dsnSeedE.XsS   - This is a blank MicroStation seed file that is used for creating
                 sheeting Geopak cross-section files. Sheeting cross-sections are
                 those that are placed on indivdual sheets. There are 100 sheets
                 in this file (there are 5 rows of 20 columns arranged in a grid).
                 The working units for this file are 1000 Sub Units per 1 Foot
                 (Master) and 10 Positional Units per Sub Unit. The higher accuracy
                 of these files compared to the rest of the IDOT MicroStation files
                 is due to the needs of the Geopak cross-section process

dsnSeedE.XsW   - This is a blank MicroStation seed file that is used for creating
                 working Geopak cross-section files. Working cross-sections are
                 those that are developed in a single file and are not yet placed on
                 indivdual sheets. The working units for this file are 1000 Sub Units
                 per 1 Foot (Master) and 10 Positional Units per Sub Unit. The higher
                 accuracy of these files compared to the rest of the IDOT MicroStation
                 files is due to the needs of the Geopak cross-section process

dsnSeedE2D.dgn - This is a blank MicroStation DGN file. The working units for this
                 file are set to 12 Inches (Sub) per 1 Foot (Master) and 60
                 Positional Units per 1 Inch (Sub). This file can be used as the
                 basis for any design project, where the project is represented
                 using State Plane coordinates. Some examples would be a
                 Photogrammetry (.PHO) file, a Design (.DGN) file, or a Right of
                 Way (.ROW) file

dsnSeedE3d.pho - This is a blank 3-D MicroStation seed file that is used for
                 creating Photogrammetry-related files. The working units for this
                 file are set to 12 Inches (Sub) per 1 Foot (Master) and 60 Positional
                 Units per 1 Inch (Sub). This file can be used where the project is
                 represented using State Plane coordinates. Some examples would be a
                 Photogrammetry Elevation file (.ELV), or used as part of developing a
                 digital terrain model (.TIN)