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I understand that certain characters need to be escaped in XML, and the ampersand is one of those characters.

According to this, there are only 5 characters that need to be escaped: What characters do I need to escape in XML documents?

My question is, if you have an ampersand, and it's NOT followed by one of those, does that mean the XML is invalid?

The reason why I'm asking is because I'm using a web service that's returning this:

<blah>&#4;</blah>

I'm trying to decide whether it's valid or invalid XML. If it's invalid, I'll ask them to fix it. If it's valid, then my php code isn't handling it correctly, and I'll need to fix it.

According to w3schools validation (http://www.w3schools.com/xml/xml_validator.asp), it's invalid, but I just wanted to make sure.

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NL3294
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1 Answers1

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An ampersand may also be part of a numeric character reference, but that particular character (&#4;) is not allowed in XML:

Character Range

[2] Char ::= #x9 | #xA | #xD | [#x20-#xD7FF] | [#xE000-#xFFFD] | [#x10000-#x10FFFF]

Minor note: you mean well-formed, not valid. See Well-formed vs Valid XML.

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kjhughes
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