What task has "&" in the following c++ code?

[SofiPashmak]

Hi all,

I need to understand the task of "&" here. it uses without varible and with varible.

//Sofi Pashmak

TScanner(const TScanner &);//What does you mean by "&" here?
void makeFilter(int noOBS, const int* observation,
                    const TFilterDescriptor& filterDescriptor);//What does you mean by "TFilterDescriptor&" here? 

[Albatross]

The & there denotes a reference!
http://www.cprogramming.com/tutorial/references.html

Best of luck.

-Albatross