A program Location Reference Table Viewer is designed to view a content of a binary location reference table (LRT), also known as a location db. The LRT plays an important role in an Unmanned Geometry Measurement System (UGMS). It provides a quick access to a list of Way Points, located along a tracks, helping to identify location of vehicle on the track. The LRT Viewer has a primary User Interface that provides access to several views to see different parts of this complexly constructed file. The file has an extention *.db. The programm also supports an extension *.lrt, but the file should have the same format.
The User Interface provides the toolbar in a main window. Buttons from the toolbar open different views in new modal windows. After opening buttons are disabled, because no data loaded in memory.
Fig.1. The User Interface before and after the data were loaded.
Load menu item 
allows to open LRT and load it content into a memory. Open file dialog shows only *.db or *.lrt files in selected folder.
If file loaded sucessfully, other buttons enabled as shown in Fig.1 on the right. A file name is displayed in the window title bar.
Fig.2. Warning
Some basic validations are performed on file opening, For example Fig.2 shows warning if GPS range is not set correctly in the file.
A first viewer shows information from LRT header. Button 
opens a new window where information from a file header is shown. Top panel displays variables and their values recorded in the header.
Fig.3. The Header View contains variables and values, and grid.
Lower part of the window shows information related to an LRT grid. After opening it may seem like all values are 0, but it is not true. Just scroll the grid right/down and non null values appear as shown in Fig 3. This grid corresponds grid in LRT. LRT grid is a grid covered the US territory by rectangular net, each cell of which is 0.1 degree latitude height and 0.1 degree longitude wide (approximately 6 * 6 miles). If cell contains way points it is marked as not null and included in the LRT grid. If value in cell is not 0 - it means that grid contains way points. A number in the cell shows an offset from the begginning of the file to the beginning of the grid block. As a rule grids connect and all together show track network outline.
Fig.4. Example of LRT Grid shown on the map
button opens a Waypoint Viewer in a separate window. The window contains grid with list of all waypoints in the the LRT. Every row shows a record that corresponds one way point. Columns show different properties of waypoints. Some properties are converted from numbers to user friendly information. For example a lst below show conversion of Way Point types from machine code to user friendly description
Normally list of waypoints is very long, it contains more than hundred thousand items. List shows items in an order that exists in LRT. To find an object a user may use Search by ID feature, which is located in a top left corner of the window.
shows a grid blocks similar to the Header View.
In difference from the Header View the grid map in Grid View has longitude and latitude coordinates (multiplied by 10) in colum/row headers.
Each not empty cell shows the number of way points in given grid block and a list of way points ID's in parenthesis, e.g. 2:{65955,65956,}.
Fig.6. The Grid View shows a number of points and point ID's in every grid
Function Search is not implemented yet.
Button Help opens a help system in a browser.