This is my attempt at a means of making Therion work well with Windows. It has worked for me since early 2008 on various versions of Windows XP. I have had problems running Loch with Vista and am not sure why, but don't think it's related to the topic discussed herein. Win7 and Win8 work (after some effort and fiddling often-times), but the functionality I describe below does not always work out.

Feel free to edit, comment or make suggestions on this page.


These pages do not describe 'the official word' on Therion. For that you should refer to The Therion Book, or pages on this wiki by those more knowledgeable. This is just my attempt to tame the beast, or a least understand it a little so that I can keep it under control.


TO DO: Add warning and guidance about issues with 5.4.0 and 5.4.1+ Briefly, if you have a previous installation on a Windows machine, select 'Install for all users', and NOT 'Install only for me'. Otherwise you'll need to manually hack the registry to unpick the carnage.

To start with you need to download and install the package intended for Windows, not the Mac, Linux or other packages. Therion does not appear to entirely follow Windows operating system norms, so there are a number of things that work a bit differently.

Default Behaviour - Text and Map Editors

Similarly to Windows, XTherion (the user interface part of Therion) uses file extensions to decide whether to open a data file in the Therion Text Editor (*.th) or in the Therion Map Editor (*.th2) by default. All other files are assumed to be configuration files, but unlike Windows, because Therion convention is not to use extensions to indicate configuration files, they cannot be opened easily directly from the Windows File Explorer interface.

Modify Behaviour to distinguish Layout and Configuration Files

To make it more Windows friendly I’ve adopted the .thc extension for ‘therion configuration’ files. To get windows to recognise these as belonging to Therion, double-click on a *.thc file, and assign it to the Wish Application in the list of available applications. The Wish Application (Windows Shell) manages the Therion application components. See

Now when you double-click on a file with a .thc file extension, Therion will generally open it in the Therion Text Editor, unless the file name starts with thconfig- in which case it will open it in the Therion Compiler. Yes, a bit odd, but it works out OK, so long as you only use the prefix thconfig- for configuration files that are intended to compile and produce output (as compared to configuration files that contain only formatting such as layouts to control for example paper size or the look of an output – these will open in the Therion Text Editor)

This all seems to work OK on Windows XP. I'm not sure about Vista. The Wish Application crashes, on some machines, when I have used it with Windows 7 or 8.

External Editors

The above will get you going using Therion and the XTherion Interactive Editor. For a number of functions XTherion IS the best way of creating and editing Therion data files. (drawing, interactive data entry, viewing and entering file names and paths for surveys and maps, locating errors) Most of the time however, I have found that other generic text editors make creating and editing the various data files MUCH easier. I expect this is the case regardless of the operating system you use.

As of somewhere around mid 2018, it seems that the default Notepad application that ships with Windows 10 does not display linefeeds correctly in the *.ini files that come with the Therion installation. The whole file displays as though it were on a single line. However using almost any other editor seems to display the files correctly.

An application I like is described in NotePad++

  • windows.txt
  • Last modified: 6 years ago
  • by brucemutton