It is possible to open several survey files at the same time. The list of open files is shown in the "Files" control of the controls panel.

The "Objects" control of the panel in the map editor contains two buttons, "Move up" and "Move down", that move the selected object up or down, respectively, in the list of the objects. Essentially, they move the line in the list of the lines that compose the ".th2" file. The "Move to" command allows to specify the line number where to move the selected object. As target line you can select the line of a scrap: by this means you move the obejct to the beginning of the target scrap.

This configuration command adds the station names to the output maps:

    export map -layout-debug station-names

To change the size of the station names one must add some MetaPost code, using the command code metapost. This is discussed in section 5.4 .

It may happen that you draw a scrap for the extended map with a certain choice of the left-right orientation, and when you compose the whole map, you need the reverse orientation. You can achieve this by adding the option -flip horizontal to the scrap definition. The other values the -flip option can take, are vertical and none.

To break a line in two at one of its intermnediate points, you must select the point, and in the "Line" control (of the panel) select the action "Edit line | Split line". If you need to break a line where there is no line-point, you must first insert a new line-point there (action "Edit line | Insert point" of the "Line" control).

When you break a line, xtherion replaces that line with two new lines, one for each of the two line pieces. When you break a line that is part of the contour of an area xtherion does not automatically update the list of lines of the contour (eg, replacing the old line with the two new ones), but maintains the reference to the old line. Therefore the compilation gives an error.

To fix it select the area. The compilation gives you a red error; click on it and xtherion brings up the map editor, with the area that raised the error, selected. Check which of its lines is missing in the scrap. You can read the line ids in the list in the "Areas" control, and each line id is displayed in the status bar when you pass over the corresponding line with the mouse (the line is highlighted light-blue). When you have found the id of the missing line, select it in the "Areas" control, and click the action "Insert" in the same control. Now you can insert the new lines in the list of the area: click on them (in the order) on the canvas. Return to the selection mode pressing the "ESC" key. Finally remove the old line id from the list (action "Delete" of the "Areas" control).

joins are also affected by line splitting. Since the line id is lost when you split a line, the "join" commands that refer to it are invalidated, and therion gives an error when you compile the project. You must assign id to one (or both) of the new lines and put this id in the "join" command(s).

Pillars are pieces of rock in the middle of the cave map. For example the portion of rock in the middle of a loop. These areas do not belong to the cave, and should not be coloured, but must be "outside" the rendered area that defines the cave passages.

To tell therion that a wall belongs to the contour of a pillar in the middle of the cave, add the option "-outline in" to it. This option specifies that the rock is "inside" the outline (the usual situation is that the rock is outside the outline).

Pits, overhang and steps cna be made transparent, to show the color of the passage underneath. The trick is to make them belong to the scrap outline and tell therion not to clip them [M. Sluka 2006.11.26],

   line overhang -outline in -clip off