retrieving form checkbox values

I have a form which I want to post multiple values from one function to another using checkboxes. Having one value is simple- the form submits the value $File and is then retrieved in the target function via $_Request['File'] So far so good. Now I want to have multiple values for $File, because $File is a value assigned to a dynamically generated list of files in a folder (which will change from folder to folder). If I have multiple <input type=checkbox name=File value=$File> then only the last value is posted to the next function and retrieved by $_Request['File'] How can I post and retrieve all values of $File or am I going about this the wrong way? Thanks