The input to Funnel is an unsorted set of data. The data is considered to be divided up into rows. In a regular "README.txt" file a row is anything on a line up to the end-of-line marker. In a binary file it is any number of bytes that you need to indicated to Funnel on the command line.
There are 2 basic ways to specify the input to funnel on the command line. One is to have it assume that the input is from standard input (usually a pipe from another command) or to specifically give funnel a file name that it will open and read.
Examples:
Specifying the input as a positional parameter
Redirecting the standard input
Piping standard input