Latexian Help > File Types
Latexian determines a file's type based on the extension in a file's name. The file type affects how code coloring, code completion, and previewing is performed for a file. For example, Latexian will apply the BibTeX coloring rules to a file if the file's name ends with a BibTeX file extension, such as ".bib". The File Types section of the Preferences allows the file type associations to be customized, although the default values should work well for most people.

File extensions can be removed and new ones added in the File Types Preferences. For each extension in the list, a file type must be specified from the following choices:
If a file in a project has an extension not listed in the File Types Preferences, then the file will open in the default external application. If you would like such a file to open in Latexian, then add its extension in the Preferences, or you can also right-click the file in the project file browser and select "Open As Text". The File Types Preferences also allow you to specify the file type for new, untitled documents; once such a document is saved, it will use its file extension to determine its type.