TXFANode.AddProcessingInstruction Method
function AddProcessingInstruction(const ATarget, AValue: AnsiString): TXFANode;
Appends an owned #text node with XMLContentKind=xckProcessingInstruction and hands back that child; ATarget is its UTF-8 XML Name and AValue holds the literal instruction data
The serialiser keeps any leading data whitespace you supply, inserts a separating space for nonempty data that starts without whitespace and emits no separator for empty data
Invalid XML characters or targets, reserved xml targets and the closing instruction delimiter inside data raise EHPDFXFAError before any child is published
The instruction leaves the parent's aggregate Value untouched; the parent owns the returned node