What is the use of projection layer

[nikhilrayaprolu]

https://github.com/iesl/dilated-cnn-ner/blob/master/src/cnn.py#L252
There is a projection layer that is mentioned in the code what is the advantage found by using the projection layer.
I couldn't find any experimental evidence being mentioned in the paper.

[strubell]

In initial experiments we didn't find the projection layer to help, so we didn't use it in the results presented in the paper.