Robots
In HTML, the robots meta tag
tells search engines and other robots whether they’re allowed to
index a page. Walter Underwood has proposed the following processing
instruction as an equivalent for XML documents:
<?robots index="yes" follow="no"?>
Robots will look for this in the prolog of any XML document
they encounter. The syntax of this particular processing instruction
is two pseudo-attributes, one named index and one named follow, whose values are either yes or no. If the index attribute has the value yes, then this page will be indexed by a
search-engine robot. If index has
the value no, then it won’t be.
Similarly, if follow has the
value yes, then links from this
document will be followed. If follow has the value no, then they won’t be.