What exactly do this TomCat init patameter setting? (trimSpaces setted on true)

I am setting the development environment for a product on which I have to work.

Into the tutorial I found that it say that I have to modify the TomCat web.xml configuration file adding these line into the section:

<init-param>
    <param-name>trimSpaces</param-name>
    <param-value>true</param-value>
</init-param>

What exactly do this setting?

Tnx