15.5.4. Using Input Parameters
Parameters declarations should be described in the <header> section
of the updategram. There should be one
<param> row for each parameter.
General syntax:
<sql:header xmlns:sql="xml-sql">
<sql:param name="PARAM_NAME" [default="DEFAULT_VALUE"]/>
...
</sql:header>
Where PARAM_NAME is the name of the parameter and
DEFAULT_VALUE is optional default of parameter
Parameters in updategram should have $PARAM_NAME
instead of a value. On processing, Virtuoso replaces
$PARAM_NAME with the corresponding value from the
<input_parameters> given to the function
xmlsql_update().