unparsed-entity-uri('pic')是什么意思
Rt
[最优解释]
The unparsed-entity-uri() function returns the URI of an unparsed entity. The name of the entity must match the passed argument. If there is no such entity an empty string is returned.

If the DTD contains the following declaration:

<!ENTITY pic SYSTEM "http://www.w3schools.com/picture.jpg" NDATA JPEG>

the following expression:

unparsed-entity-uri('pic')

will return the URI for the file "picture.jpg".