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  5. 3.8.8.2. Non-Standard Properties 

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#  3.8.8.2. Non-Standard Properties

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##  Property Name

Any property name with a "X-" prefix

##  Purpose

This class of property provides a framework for defining non-standard
properties.

##  Value Type

The default value type is TEXT. The value type can be set to any value type.

##  Property Parameters

IANA, non-standard, and language property parameters can be specified on this
property.

##  Conformance

This property can be specified in any calendar component.

##  Description

The MIME Calendaring and Scheduling Content Type provides a "standard
mechanism for doing non-standard things". This extension support is provided
for implementers to "push the envelope" on the existing version of the memo.
Extension properties are specified by property and/or property parameter names
that have the prefix text of "X-" (the two-character sequence: LATIN CAPITAL
LETTER X character followed by the HYPHEN- MINUS character). It is recommended
that vendors concatenate onto this sentinel another short prefix text to
identify the vendor. This will facilitate readability of the extensions and
minimize possible collision of names between different vendors. User agents
that support this content type are expected to be able to parse the extension
properties and property parameters but can ignore them.

At present, there is no registration authority for names of extension
properties and property parameters. The value type for this property is TEXT.
Optionally, the value type can be any of the other valid value types.

##  Format Definition

This property is defined by the following notation:

    
    
     x-prop = x-name *(";" icalparameter) ":" value CRLF

##  Example

The following might be the ABC vendor's extension for an audio-clip form of
subject property:

    
    
     X-ABC-MMSUBJ;VALUE=URI;FMTTYPE=audio/basic:http://www.example.
      org/mysubj.au

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RFC-5545/3-8-8-1-iana-properties.html) [ Next article: 3.8.8.3. Request Status
Next  ](/iCalendar-RFC-5545/3-8-8-3-request-status.html)

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document should be referred to if there are any errors or discrepancies found
in this document. _

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