How to proper initialize the nvelocity engine?

As I saw in some examples, and tried to understand throughout the velocity site, there are three ways of initiali开发者_开发技巧zing the velocityengine:

- With the default configurations : .Init()

- With the default configurations, plus the properties in a file : .Init(string)

- With the default configurations, plus the properties in a collection : .Init(Commons.Collections.ExtendedProperties)

But i've found little explanation on how these work. Per example, in a app i've downloaded:

VelocityEngine engine = new VelocityEngine();
ExtendedProperties props = new ExtendedProperties();
props.AddProperty("file.resource.loader.path", new ArrayList(new string[] { ".", @".\Templates" }));
engine.Init(props);

Beyond the obvious assumption, what is "file.resource.loader.path"?

What are the other properties i can change, and how can i change them (I mean, using the addproperty, or if there other ways please, specify)?

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Here is a list of available properties.