We say in 3.6.3.3:

<quote>
Within the declaration of an overriding component (that is, a component whose declaration is a child of xsl:override), where the overridden component has public visibility, it is possible to use the name xsl:original as a symbolic reference to the overridden component:

<snip/>
* Within an overriding stylesheet function, xsl:original() may be used to call the overridden stylesheet function.

</quote>

There's a need for more precision here.

(a) a function call on xsl:original will usually have arguments

(b) symbolic references to functions may also appear in the form of partial function application (e.g. xsl:original(?, 3)), or named function references (e.g. xsl:original#2). We need to make it clear that these are legal.

(c) we should make it clear that xsl:original cannot be used in static expressions, e.g. within use-when. (This also applies to the variable reference $xsl:original)

(d) we should make it clear that dynamic references to xsl:original, e.g in function-available(), function-lookup(), or xsl:evaluate, will not succeed. Again this also applies to the variable reference $xsl:original.