No, it is neither.
XML has explicit delimiters to clearly mark up processing instructions.
You are using them for what they are intended.
A different take on the issue is this. The SGML/XML model is
elements/entities(e.g. resources)/processing instructions.
XML piggybacks everything on top of element structure.
This is distinct from, e.g., PDF which piggybacks element
structure (such as it has) on top of processing.
-ricko