Unparsing - that's what we call it
Two frequently referenced online sources give definitions of the word "unparse", so we're going to stop apologizing for it.
Everyone agrees about the term "parsing", but the inverse of that, well there has been some controversy. Some people use the term "serialization", others prefer "marshalling". In DFDL we have long used the term "unparsing", but somehow that made people uncomfortable in that it felt like we were making up words that didn't really exist.
These aren't the Oxford English dictionary, but they represent sufficient usage and agreement that we're going to stop apologizing for the term unparsing.