In Déjà Vu, there are 3 sets of filter properties:

• The General Filter Options, that you can view and change by accessing the Options dialog.
• The Project Filter Options, that you can view and change by accessing the Project Properties dialog.
• The Filter Properties of each individual file in a project, that you can view and change using the Filter Properties Window.

These sets of Filter Properties are arranged hierarchically, so that the properties of each set are determined by those of the set above it in the hierarchy, but this only happens in specific ways. Also, each set of Filter Properties is used in specified situations, so if you modify the wrong set of filter properties in any particular situation, you may find that Déjà Vu is not using the new configuration even though you expect it to.

How are the sets of filter properties related?

The General Filter Options are the highest in the hierarchy. The Project Filter Options are derived from them, and the filter properties of individual files in the project are in turn derived from those of the project.

When a new project is created, a new set of Filter Options for the project is created too. These filter options are copied from the General Filter Options (unless you are using a template to create the project), but they are separate from them. This means that, when you change the General Filter Options, the changes you make will be applied to any new project you create, but they will not have any effect on existing projects.

When a new file is added to a project, either during project creation or afterwards, a new set of Filter Properties is created for this file. These properties are copied from the Filter Options of the project itself. This means that, when you change the Filter Options of a project, the changes you make will be applied to any new file you add to the project, but they will not have any effect on the files that are already added to the project.

The Filter Properties for an individual file are the lowest in the hierarchy. Changing the filter properties for an individual file in a project will affect that file and nothing else.

Why do the filter properties work this way?

This system may at first sight appear to be overly complicated, but it actually gives you a lot of control over how Déjà Vu handles the files you add to projects once you understand how the filter properties are used.

Having a set of Filter Options for a project that are related to, but distinct from, the General Filter Options allows you to configure the filters used by Déjà Vu with the options that best suit the kind of files you are most likely to translate, while giving you the liberty to modify the Filter Options for a single project that contains files that require different options without having to modify your General Filter Options. For example, you might have Déjà Vu configured to import Word documents ignoring hidden text, but need to import the hidden text as well for just a few documents; by configuring a new project to import hidden text in Word documents and then adding all these documents to it, you can handle this situation easily.

Similarly, having individual filter properties for each file in a project allows you to use a set of options for your filters that suits most of the documents in a single project, while giving you the liberty to tweak the filter properties for a single file that happens to need it. For example, you may have Déjà Vu configured to ignore hidden text in Word documents, but wish to import the hidden text from a single file.

The hierarchy of Filter Options used begins with the general and flows down to the specific. Therefore, when you are configuring the different sets of filter options, you must begin by considering your general needs, and configure the General Filter Options appropriately, then consider what you need for a project, and then consider what you need for specific files in the project. By thinking in these terms, you can greatly reduce the amount of configuration you need to do to the filter properties of the documents you work with.

What are the consequences of this system?

Understanding the way filter properties are created and inherited when you create new projects or add files to existing projects will help you understand certain behaviors of Déjà Vu that may have seemed mysterious or even dysfunctional at first glance. For example:

• You may be surprised to find that changing the default options for a filter used to import a particular file type in the General Filter Options has no effect on the project you are currently working on. This is because your current project has its own set of Filter Properties that have not been changed. To ensure that the changes you made to the General Filter Options are applied to an existing project, you must duplicate those changes in the Project's Filter Options or create a whole new project.
• If you make changes to the General Filter Options, and then create a new project based on a Project Template you already had, you will find that the changes you made were not applied. This is because the project template contains its own set of Project Filter Options, and when you create a new project based on that template, the new project's Filter Options are copied from the template, not the General Filter Options.
  In this situation, you must either create a new project without using the template or, if you wish to continue using the template, create the project with the template regardless, then modify the new project's Filter Options as needed, and save these changes to a new template.