postfield
Specifies a field name and value for transmission to an origin server during a URI request. The actual encoding of the name and value will depend on the method used to communicate with the origin server.

attributes

name
Specifies the variable name.
value
Specifies the variable value.
xml:lang
Specifies the natural or formal language in which the document is written.
id
Provides an element with a unique name within a single deck.
class
Affiliates an element with one or more classes.