Request accessor is a syntactical construct of the form:
%[name]
where name denotes a part of the incoming request to access and square brackets are part of the construct. Accessors are interpreted and replaced with the value of the corresponding part of the request. Some accessors take an argument, which is specified after accessor name and is delimited from it by one or more whitespace characters.
The following accessors are defined:
Request URL.
Request path.
Query part.
The value of the query parameter name.
The value of HTTP header name.
Hostname part of the Host header. If the latter
does not include port number, it is equivalent to
%[header host]
.
If the value of the Host
header includes port number,
‘%[port]’ expands to port number with the leading colon
character. Otherwise, it expands to empty string.