Perl provides a simple report-writing template, called a format. A format defines a constant part (the column headers, labels, fixed text, or whatever) and a variable part (the current data you're reporting). The shape of the format is very close to the shape of the output, as with formatted output in COBOL or the
using clauses of some BASICs.
Using a format consists of doing three things:
Most often, the first step is done once (in the program text so that it gets defined at compile time), and the other two steps are performed repeatedly.