Image Rendering HTTP encoding

Last update: 2022-03-04
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Command values must be http-encoded using %xx escape sequences, such that the value strings do not include the reserved characters ‘=’, ‘&’, and ‘%’.

Otherwise, standard HTTP encoding rules apply. The HTTP specification requires encoding of the unsafe characters such as ’ ’ (space), ‘"’(double-quote), ‘#’, ‘%’, ‘<’, and ‘>’, as well as any control characters, such as <return> and <tab>.

Caution: Curly braces { } used as request-nesting delimiters must not be encoded. Certain email clients unfortunately encode curly braces in embedded HTTP request. Should this issue be a problem, Image Rendering allows use of parentheses ( ) instead of curly braces.

Example

…&$text=rate&weight=85% 27#&…

The above request fragment must be encoded as follows:

…&$text=rate%26weight%3D85%25%2027%23&…

See also

HTTP/1.1 Specification (RFC 2616)

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