Token Replacement in DotNetNuke
Examples:

[Object:Properties]
Welcome [User:Username] to the forum.
Dear [User:FirstName],
[Object:Properties|Format]
[User:Username|Welcome {0} to the forum]
[DateTime:Now|D]
[Object:Properties|Format|IfEmptyReplacement]
[User:Username|Welcome {0} to the forum.|Welcome guest, please login to access the
forum.]
MSDN: Here is the link to the Date Format Info Class, this provides the format characters for
formatting the date and time tokens:
http://msdn.microsoft.com/library/default.asp?url=/library/enus/
cpref/html/frlrfsystemglobalizationdatetimeformatinfoclasstopic.asp

Tokens
Token Description

[Portal:Currency] Currency String
[Portal:Description] Portal Description
[Portal:Email] Portal Admin Email
[Portal:FooterText] Portal Copyright Text
[Portal:HomeDirectory] Portal (relative) Path of Home Directory
[Portal:LogoFile] Portal Path to Logo file
[Portal:PortalName] Portal Name
[Portal:PortalAlias] Portal URL
[Portal:TimeZoneOffset] Difference in minutes between Portal default time and UTC
[User:DisplayName] User’s Display Name
[User:Email] User’s Email Address
[User:FirstName] User’s First Name
[User:FullName] [deprecated]
[User:LastName] User’s Last Name
[User:Username] User’s Login User Name
[Membership:Approved] Is User Approved?
[Membership:CreatedDate] User Signup Date
[Membership:IsOnline] Is User Currently Online?
[Profile:<Property>]
Use any default or custom Property defined for user profiles as listed in Profile
Property Definition section of Manage User Accounts. Please use non‐localized
Property titles only.
[Tab:Description] Page Description Text for Search Engine
[Tab:EndDate] Page Display Until Date
[Tab:FullUrl] Page Full URL
[Tab:IconFile] Page Relative Path to Icon file
[Tab:KeyWords] Page Keywords for Search Engine
[Tab:PageHeadText] Page Header Text
[Tab:StartDate] Page Display from Date
[Tab:TabName] Page Name
[Tab:TabPath] Page Relative Path
[Tab:Title] Page Title (Window Title)
[Tab:URL] Page URL
[Module:Description] Module Definition Description
[Module:EndDate] Module Display Until Date
[Module:Footer] Module Footer Text
[Module:FriendlyName] Module Definition Name
[Module:Header] Module Header Text
[Module:HelpUrl] Module Help URL
[Module:IconFile] Module Path to Icon File
[Module:ModuleTitle] Module Title
[Module:PaneName] Module Name of Pane where UDT resides
[Module:StartDate] Module Display from Date
[DateTime:Now] Current Date and Time
[Ticks:Now] CPU Tick Count for Current Second
[Ticks:Today] CPU Tick Count since Midnight
[Ticks:TicksPerDay] CPU Ticks per Day (for calculations)

Hope this is helpful .