clarify meaning of AssertItems and QueryItems in BiMetaTrans source-level documentation
* inputs are expected to be ground, meaning they should not contain
* free variables.
*
+ * A RuleML/XML document is assumed to contain an optional Assert
+ * element (with zero or more children) and zero or more Query
+ * elements. The children of the Assert element are the Items of
+ * AssertItems, while the Items of QueryItems each correspond to a
+ * single Query element.
+ *
* parse_ruleml/3 is meant to subsume an invertible function in the
* sense that the top-level query
*
