Basic question

[WILLIAM SCHMIDT]

In several places in the Python documentation I have run across an extra "r" that I can not explain:


*****************************
In sys.path after the open bracket:
       sys.path = [r'd:\temp']

In the on line help in the DATA section (towards the end):

>>> help('sys')
Help on built-in module sys:

~~~~  truncated ~~~~

DATA
    exec_prefix = r'C:\Python25'
    executable = r'C:\Python25\pythonw.exe'
    path = [r'C:\Python25\Lib\idlelib', r'C:\Python25\python25.zip', r'C:\...
    prefix = r'C:\Python25'
    version = '2.5.1 (r251:54863, Apr 18 2007, 08:51:08) [MSC v.1310 32 bi...
*****************************

Can someone explain what that "r" is doing and where I would find it in the documentation?

Thank you in advance for your assistance.

William T. Schmidt