There are some special characters in my template or FXG, but they don't appear in the final image, or I receive an error message.
Basic Template and W2P URLs sometimes include certain characters that have special meaning to the servers, but which you want to display as text. Examples of these include ampersand, equals, dollar sign, and so on. Encode these characters using their HTTP encoding. You can find a list of some of these encodings here: http://www.w3schools.com/tags/ref_urlencode.asp
For example, ampersand is encoded as "%26."
Some characters have special meaning for the underlying RTF or FXG syntax of the target document, such as the plus sign or backslash. Double encode these characters, because the server strips out the first layer as it passes through the Platformserver. For example, double encode the plus sign as "%252b." The Platformserver converts it to "%2b" when the request is received. Then, the rendering engine interprets it as the literal '+' character, instead of treating it as FXG whitespace.