[Definition: CDATA sections may occur anywhere character data may occur; they are used to escape blocks of text containing characters which would otherwise be recognized as markup. CDATA sections begin with the string "<![CDATA[" and end with the string "]]>":]
CDATA Sections
[18]    CDSect    ::=    CDStart CData CDEnd
[19]    CDStart    ::=    '<![CDATA['
[20]    CData    ::=    (Char* - (Char* ']]>' Char*))
[21]    CDEnd    ::=    ']]>'

Within a CDATA section, only the CDEnd string is recognized as markup, so that left angle brackets and ampersands may occur in their literal form; they need not (and cannot) be escaped using "&lt;" and "&amp;". CDATA sections cannot nest.

An example of a CDATA section, in which "<greeting>" and "</greeting>" are recognized as character data, not markup:

<![CDATA[<greeting>Hello, world!</greeting>]]>
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所以 CDATA方法是不究竟不彻底的, 不能真正地用来放二进制数据. 即使不考虑]]>这个结束符, 用下面的办法生成从0到255的所有字节值放在 CDATA段中不能被 xerces 所解析
for i in $(seq 0 1 255); do printf "%02x" $i; done | xxd -r -ps > 0_255.bin

我的目标是设计一种XML格式, 需要携带大量的任意二进制数据, 要求格式紧凑高效, 欢迎指教