Nothing similar and a not-so-frequent Apps Script question - google-apps-script

Question

Through trial and error I modified the below line of code to print the range B4:I59. Can someone help me to understand what the code says and/or how do I read it?
Original code
var printRange = '&c1=0' + '&r1=0' + '&c2=7' + '&r2='+row2; // B2:APn
Modified Code
var printRange = '&c1=1' + '&r1=2' + '&c2=9' + '&r2='+row2; // B4:I59
This is my whole code:
//* Print Extentions
function printPdf() {
SpreadsheetApp.flush();
var ss = SpreadsheetApp.getActiveSpreadsheet();
var sheet = ss.getActiveSheet();
var gid = sheet.getSheetId();
var pdfOpts = '&size=A4&fzr=false&landscape=false&fith=true&gridlines=false&printtitle=false&sheetnames=false&pagenum=UNDEFINED&attachment=false&gid='+gid;
var row2 = 59;
var printRange = '&c1=1' + '&r1=2' + '&c2=9' + '&r2='+row2; // B4:I59
var url = ss.getUrl().replace(/edit$/, '') + 'export?format=pdf' + pdfOpts + printRange;
var app = UiApp.createApplication().setWidth(200).setHeight(50);
app.setTitle('Print Extentions List');
var link = app.createAnchor('Download PDF', url).setTarget('_new');
app.add(link);
ss.show(app);
}
The code works

Answer 1

In the line:
var url = ss.getUrl().replace(/edit$/, '') + 'export?format=pdf' + pdfOpts + printRange;
You are defining a URL that will allow you to export the given spreadsheet as a PDF using the specified options. The & symbols separate arguments you are passing into the URL.
This document gives a nice description of the parameters you are using. According to that document:
//r1=Start Row number - 1 row 1 would be 0 , row 15 wold be 14
//c1=Start Column number - 1 column 1 would be 0, column 8 would be 7
//r2=End Row number
//c2=End Column number