As mentioned at F2F Prague 2016, Day 2, and in Bug 29379, comment#4 and Bug 29379, comment#5, we decided that the description of this error should be updated to be in line with other parts of the spec that require the initial mode/function/template to be public.

Current text:

<quote>
[ERR XTDE0045] It is a dynamic error if the invocation of the stylesheet specifies an initial mode (other than the unnamed mode) that does not match either the expanded QName in the name attribute of an xsl:mode declaration, or the expanded QName in the mode attribute of any template defined in the stylesheet.
</quote>

Which is not in line with 6.6.1:

"A named mode is not eligible to be used as the initial mode if its visibility is private."

We may also revise the wording a bit for the last part of the XTDE0045 error description, as this is no longer true for packages. I suggest something like:

<suggestion>
[...]or the expanded QName in the mode attribute of any template defined in the stylesheet if the implicit or explicit value of declared-modes equals false.
</suggestion>