Oplog entries are very strongly structured. The applyOps command inspects them to ensure they are well formed, and to perform authorization checks. They are a good candidate for IDLification. An IDL generated parser would more efficiently extract all the relevant fields, without having to perform multiple linear scans across the provided BSON objects.

Note that the existing IDL descriptions for oplog tokens assume that 'ts' fields are mandatory. This is not necessarily be true for tokens presented via applyOps. Some adjustment, or contextualization of parsing will be required.