Verfying the Integrity of Your Copy of a Certified Series 

1.	Why are Certified Series important?

Certified Series are the very best collections available, providing the most episodes available in the best possible sound.  Many Certified Series also contain many extra features, such as excellent audio files describing the Series and stars, and CD artwork designed especially for each Series.

2.	Why is verifying my copy of a Certified Series important?

Certified Series exist to avoid circulating series that are in less than desirable condition.    The members of the Old Time Radio Researchers Group are expending great effort to assemble and distribute the Certified Series.  Maintaining the integrity of each Series is important to preserve the quality and dependability of the Series.   Respecting the effort of the Researches requires preserving the authenticity of the Series.

Having a verified copy means that you possess exactly what the creators of the Certified Series intended.  Specifically:

A.	No file has been removed from the Series.
B.	No unauthorized file has been added to the Series 
C.	No file has been replaced by some other, perhaps similar, file.
D.	No file has been renamed, re-titled, or re-dated, 
E.	No file is corrupt -- every file is absolutely correct.

Further, retaining only correct copies of each Series is important since it reduces the possibility of multiple, possibly inconsistent, versions of a Series being disseminated. 

3.	How do I verify a Certified Series?

Verifying is simple.  Once you have the right program, it takes only a few minutes per Series.

4.	What are the CRC files?

Every Certified Series has a file with the extension *.CRC, for example,

Box 13 (OTRR Certified – Version 1).CRC

This file has information about every file in the Series distribution.  It has data about the names of each file, as well as a “check sum” or “hash value” of each file.  This information can be used to verify that the file is exactly the same as the file that the Series editors intended.  In some cases, the CRC file can even be used to repair a corrupted file.

5.	How do I use the CRC files?

For Windows users:  You will need a copy of the program CDCheck, which you can obtain at
http://www.elpros.si/CDCheck/download.php

CDCheck is free for personal use, though you have to go to their “Order” page and register to get a free license:

	http://www.elpros.si/CDCheck/helplink.php?helpfn=registration

CDCheck is easy to use.  Take a look at their instructions and help.  In summary:

A.	In the main window, choose the topmost folder of a Certified Series.
B.	Click the “Check” button in the toolbar.
C.	You will get a popup window with options.  Choose the following:

a.	“Automatic detection” for hash files. 
b.	“Report files without hash value when hash files are detected”
c.	“Report hash values for which files do not exist”

Click “Continue” at the bottom of the popup.
D.	After a few minutes, you will get a summary of errors and warnings. 

Note:  If you store multiple Series on your hard drive, you can verify your entire collection of Series at once by choosing the high level folder that contains your collection.

If all goes well, you have a perfect copy of the Certified Series:

A.	CDCheck will give you only one small “note” telling you the name of the CRC file that it found and used.
B.	Congratulations!  You can feel good knowing that your Series is accurate and exact.

If you get warning or errors, then something is not right….

6.	What kinds of warnings or errors might I get?

The set of possible warnings and errors is listed in the CDCheck help file in the section on “Error Codes”. 

Some of the more common problems:

 Warnings:

	Hash value not present in any hash file! (code: 40)

•	There is an extra (unauthorized) file in the distribution.  (The CRC file does not know about the file.)

Directory present in hash file not found (code: 44)

•	You are missing a directory/folder.   

File present in <folder> .  CRC not found (code: 45)

•	You are missing a file.

Errors:

	CRC-32 hash check failed (code: 46)

•	Either the file is corrupted or the file has been replaced by a different file.

7.	What do I do if I get warnings or errors?

Try to obtain the correct file.  Based on how you received the distribution:

a.	Distribution group: Contact the sender of the disk to resend checked disk.
b.	Streamload: If file was not available for download, contact sender to upload again.
c.	Secure Hub:  Download the file again or use a different Librarian.
d.	Our Redistribution group: Contact the sender of the disk to resend checked disk.
e.	The OTRResearchers group library: Contact librarian to resend checked disk. 
f.	FTP: Download the file again.

8.	What do I do if I suspect the CRC file is wrong?

a.	Download from our group’s file section, library hub or FTP site, from the folder holding the certified CRC files.
b.	Ask the group librarian to send you the CRC file in question.  The master disks in the library never leave; only copies are borrowed.  These files are small enough that most e-mail accounts will allow them.

Following these steps should insure that the CD in your collection is identical to the CD that was certified and released by the OldTimeRadioResearchersGroup at Yahoo. As stated before, we want to distribute only certified series. The CD is the certified item, and the sum of all files included make up the certified series. 

Future distributions of any certified series should be the checked CD in its original format.  Only in this way can we guarantee everybody will enjoy the work of the many hard working members of the OldTimeRadioResearchersGroup at Yahoo.