Here's A List of Apple iTunes Match Support Docs.

If you are new to iTunes Match or are experiencing problems, reading these support documents is a good place to start.

How To Subscribe to iTunes Match

http://support.apple.com/kb/HT4914

Also includes information on what types of files are eligible for iTunes Match, file size limitations, how iTunes Match handles DRM, what counts towards the 25,000 song limit. Links to most of the support documents listed below.

Apple IDs and iCloud

http://support.apple.com/kb/HT4895

Includes links to documents related to using the same Apple ID for Store purchases and iCloud, using different IDs for each, using MobileMe accounts.

Associating A Device or Computer to your Apple ID

http://support.apple.com/kb/HT4627

Explains how to access your account, check to see what devices are associated with it and how to delete devices. Also explains the 90-day limit on associating devices and gives you a way to track how much time remains on the 90-day limit.

Troubleshooting iTunes Match

http://support.apple.com/kb/ts4054

Outlines steps to take if some songs are missing from iCloud, shows you how to enable view options to see iCloud Status, includes information on file formats used by iCloud.

Understanding the iCloud Status Icons

http://support.apple.com/kb/ts4124

How To Delete Songs From iCloud

http://support.apple.com/kb/ht4915

How to Add A Computer or IOS Device to iTunes Match

http://support.apple.com/kb/ht4913