In the vast majority of cases where we have constructs that depend on the context item, we have introduced a variant of the construct that allows the relevant item to be supplied explicitly as an operand. Examples are xsl:copy, xsl:number, fn:id, fn:key. This allows the construct to be used without the artifice of having to set the context item using something like xsl:for-each; it is also useful internally within an implementation because it allows the form of the construct that uses the context implicitly to be rewritten to the form where the dependency is explicit, for example id('x') can be rewritten as id('x', /).

The unparsed-entity-uri() and unparsed-entity-public-id() functions have not had this treatment: they can only be applied to the document containing the context item.

I would therefore like to propose introducing a two-argument form of these functions taking a node as the second argument, defaulting to the context node if the argument is not supplied.