A DVT project can have zero to many project natures.

To manually enable a language parser, add the lang directive inside a <name>.ls file corresponding to your current <name>.build file.

When no language is specified, the extension will try to automatically detect the natures based on the nature directive in an Eclipse .project file when migrating from a DVT Eclipse project. If no nature is found, you'll be asked to select the natures manually.

After the languages are determined, they will be serialized inside the <name>.ls file.

To turn on/off a specific nature for a project, use the DVT: Change Languages... command from Command Palette.