2.1.12 [XML] Section 3.4, Conditional Sections
The specification states:
Validity constraint: Proper Conditional Section/PE Nesting If any of the "<![", "[", or "]]>" of a conditional section is contained in the replacement text for a parameter-entity reference, all of them MUST be contained in the same replacement text.
IE9 Mode, IE10 Mode, IE11 Mode, and EdgeHTML Mode (All Versions)
All the syntactic elements that are referred to in a conditional section (<![, [, and ]]>) are not checked to be present in the same replacement text.