Restrictions and Recommendations on File Name, Length, Size and Invalid Character

New Blocked File Types
If you were familiar with the WSS 2.0 list, there are some new Blocked File Types: .asmx, .rem, .resx, .soap, or .ashx.  If they existed before upgrade they are no longer visible or cannot be opened after upgrade.  These file extensions have been added to the list of blocked file extensions.


You now have the ability to make differences between farm wide blocked file types and web application blocked file types.  If you want to un block it, it needs to be removed at both farm and application levels, but you can add specific blocked files for a single web application.  The farm level block list for example will override anything removed at the web application level.

Site Names

• In WSS Site Names may not contain the following characters: \ / : * ? " < > | # { } % & " ~ +
• You cannot start a site name, sub site name, or a site group name with an underscore (_) character or with the period character (I recommend avoiding the (_) underscore in site names)
• You cannot use the period character consecutively in the middle of a site name
• You cannot use the period character at the end of a site name 

File Names

• Invalid characters: " # % & * : < > ? \ / { | } ~
• Cannot be longer than 128 characters
• You cannot use the period character consecutively in the middle of a file name
• You cannot use the period character at the end of a file name
• You cannot start a file name with the period character

Folder Names

• You cannot use the following characters anywhere in a folder name or a server name:  ~ # % & * { } \ : < > ? / | "
• Cannot be longer than 128 characters
• You cannot use the period character consecutively in the middle of a folder name
• You cannot use the period character at the end of a folder name
• You cannot start a folder name with the period character
• Max File Upload/Download Sizes
• The default max single file upload size is 50 MB by default for a web application. 
• Microsoft IT limits their environment at 100 MB, and the maximum that the product itself can handle or support is 2GB which is essentially a SQL limit.  By setting the limit to blank will essentially support what SQL will support.

Increase the maximum upload size

• Click Start, point to All Programs, point to Administrative Tools, and then click SharePoint Central Administration.
• Under Virtual Server Configuration, click Configure virtual server settings.
• On the Virtual Server List page, click the virtual server you want to change.
• On the Virtual Server Settings page, under Virtual Server Management, click Virtual server general settings.
• Under Maximum upload size, type the maximum file size (in MB) that you want to allow to be uploaded.
• Click OK.

Get into the SharePoint Central Administration Site

• Select "Application Management"
• Under the "SharePoint Web Application Management" section select "Web Application General Settings"
• Change the "Maximum Upload Size" 

If IIS is timing out when you upload large files, you can configure the Connection timeout setting in IIS to allow more than the default 120 seconds (2 minutes).

Tune the IIS connection timeout

• Click Start, point to All Programs, point to Administrative Tools, and then click Internet Information Services (IIS) Manager.
• Right-click the virtual server you want to configure, and then click Properties.
• Click the Web Site tab.
• In the Connections section, in the Connection timeout box, type the number of seconds you want IIS to wait before timing out.
• Click OK.

Reference: http://blogs.msdn.com/b/joelo/archive/2007/06/27/file-name-length-size-and-invalid-character-restrictions-and-recommendations.aspx